diff --git a/spec/matchers/contain_matcher_spec.cr b/spec/matchers/contain_matcher_spec.cr
index b79e345..be5031d 100644
--- a/spec/matchers/contain_matcher_spec.cr
+++ b/spec/matchers/contain_matcher_spec.cr
@@ -1,327 +1,386 @@
 require "../spec_helper"
 
 describe Spectator::Matchers::ContainMatcher do
-  describe "#match?" do
-    context "with a String" do
-      context "one argument" do
-        context "against a matching string" do
-          it "is true" do
-            value = "foobarbaz"
-            search = "bar"
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new({search})
-            matcher.match?(partial).should be_true
-          end
+  describe "#match" do
+    context "returned MatchData" do
+      describe "#matched?" do
+        context "with a String" do
+          context "one argument" do
+            context "against a matching string" do
+              it "is true" do
+                value = "foobarbaz"
+                search = "bar"
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new({search})
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
 
-          context "at the beginning" do
-            it "is true" do
-              value = "foobar"
-              search = "foo"
-              partial = new_partial(value)
-              matcher = Spectator::Matchers::ContainMatcher.new({search})
-              matcher.match?(partial).should be_true
+              context "at the beginning" do
+                it "is true" do
+                  value = "foobar"
+                  search = "foo"
+                  partial = new_partial(value)
+                  matcher = Spectator::Matchers::ContainMatcher.new({search})
+                  match_data = matcher.match(partial)
+                  match_data.matched?.should be_true
+                end
+              end
+
+              context "at the end" do
+                it "is true" do
+                  value = "foobar"
+                  search = "bar"
+                  partial = new_partial(value)
+                  matcher = Spectator::Matchers::ContainMatcher.new({search})
+                  match_data = matcher.match(partial)
+                  match_data.matched?.should be_true
+                end
+              end
+            end
+
+            context "against a different string" do
+              it "is false" do
+                value = "foobar"
+                search = "baz"
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new({search})
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against a matching character" do
+              it "is true" do
+                value = "foobar"
+                search = 'o'
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new({search})
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
+
+              context "at the beginning" do
+                it "is true" do
+                  value = "foobar"
+                  search = 'f'
+                  partial = new_partial(value)
+                  matcher = Spectator::Matchers::ContainMatcher.new({search})
+                  match_data = matcher.match(partial)
+                  match_data.matched?.should be_true
+                end
+              end
+
+              context "at the end" do
+                it "is true" do
+                  value = "foobar"
+                  search = 'r'
+                  partial = new_partial(value)
+                  matcher = Spectator::Matchers::ContainMatcher.new({search})
+                  match_data = matcher.match(partial)
+                  match_data.matched?.should be_true
+                end
+              end
+            end
+
+            context "against a different character" do
+              it "is false" do
+                value = "foobar"
+                search = 'z'
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new({search})
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
             end
           end
 
-          context "at the end" do
-            it "is true" do
-              value = "foobar"
-              search = "bar"
-              partial = new_partial(value)
-              matcher = Spectator::Matchers::ContainMatcher.new({search})
-              matcher.match?(partial).should be_true
+          context "multiple arguments" do
+            context "against matching strings" do
+              it "is true" do
+                value = "foobarbaz"
+                search = {"foo", "bar", "baz"}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
+            end
+
+            context "against one matching string" do
+              it "is false" do
+                value = "foobarbaz"
+                search = {"foo", "qux"}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against no matching strings" do
+              it "is false" do
+                value = "foobar"
+                search = {"baz", "qux"}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against matching characters" do
+              it "is true" do
+                value = "foobarbaz"
+                search = {'f', 'b', 'z'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
+            end
+
+            context "against one matching character" do
+              it "is false" do
+                value = "foobarbaz"
+                search = {'f', 'c', 'd'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against no matching characters" do
+              it "is false" do
+                value = "foobarbaz"
+                search = {'c', 'd', 'e'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against a matching string and character" do
+              it "is true" do
+                value = "foobarbaz"
+                search = {"foo", 'z'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
+            end
+
+            context "against a matching string and non-matching character" do
+              it "is false" do
+                value = "foobarbaz"
+                search = {"foo", 'c'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against a non-matching string and matching character" do
+              it "is false" do
+                value = "foobarbaz"
+                search = {"qux", 'f'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against a non-matching string and character" do
+              it "is false" do
+                value = "foobarbaz"
+                search = {"qux", 'c'}
+                partial = new_partial(value)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
             end
           end
         end
 
-        context "against a different string" do
-          it "is false" do
-            value = "foobar"
-            search = "baz"
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new({search})
-            matcher.match?(partial).should be_false
-          end
-        end
+        context "with an Enumberable" do
+          context "one argument" do
+            context "against an equal value" do
+              it "is true" do
+                array = %i[a b c]
+                search = :b
+                partial = new_partial(array)
+                matcher = Spectator::Matchers::ContainMatcher.new({search})
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
 
-        context "against a matching character" do
-          it "is true" do
-            value = "foobar"
-            search = 'o'
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new({search})
-            matcher.match?(partial).should be_true
-          end
+              context "at the beginning" do
+                it "is true" do
+                  array = %i[a b c]
+                  search = :a
+                  partial = new_partial(array)
+                  matcher = Spectator::Matchers::ContainMatcher.new({search})
+                  match_data = matcher.match(partial)
+                  match_data.matched?.should be_true
+                end
+              end
 
-          context "at the beginning" do
-            it "is true" do
-              value = "foobar"
-              search = 'f'
-              partial = new_partial(value)
-              matcher = Spectator::Matchers::ContainMatcher.new({search})
-              matcher.match?(partial).should be_true
+              context "at the end" do
+                it "is true" do
+                  array = %i[a b c]
+                  search = :c
+                  partial = new_partial(array)
+                  matcher = Spectator::Matchers::ContainMatcher.new({search})
+                  match_data = matcher.match(partial)
+                  match_data.matched?.should be_true
+                end
+              end
+            end
+
+            context "against a different value" do
+              it "is false" do
+                array = %i[a b c]
+                search = :z
+                partial = new_partial(array)
+                matcher = Spectator::Matchers::ContainMatcher.new({search})
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
             end
           end
 
-          context "at the end" do
-            it "is true" do
-              value = "foobar"
-              search = 'r'
-              partial = new_partial(value)
-              matcher = Spectator::Matchers::ContainMatcher.new({search})
-              matcher.match?(partial).should be_true
+          context "multiple arguments" do
+            context "against equal values" do
+              it "is true" do
+                array = %i[a b c]
+                search = {:a, :b}
+                partial = new_partial(array)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_true
+              end
             end
-          end
-        end
 
-        context "against a different character" do
-          it "is false" do
-            value = "foobar"
-            search = 'z'
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new({search})
-            matcher.match?(partial).should be_false
+            context "against one equal value" do
+              it "is false" do
+                array = %i[a b c]
+                search = {:a, :d}
+                partial = new_partial(array)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
+
+            context "against no equal values" do
+              it "is false" do
+                array = %i[a b c]
+                search = {:d, :e}
+                partial = new_partial(array)
+                matcher = Spectator::Matchers::ContainMatcher.new(search)
+                match_data = matcher.match(partial)
+                match_data.matched?.should be_false
+              end
+            end
           end
         end
       end
 
-      context "multiple arguments" do
-        context "against matching strings" do
-          it "is true" do
-            value = "foobarbaz"
-            search = {"foo", "bar", "baz"}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_true
-          end
-        end
-
-        context "against one matching string" do
-          it "is false" do
-            value = "foobarbaz"
-            search = {"foo", "qux"}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against no matching strings" do
-          it "is false" do
-            value = "foobar"
-            search = {"baz", "qux"}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against matching characters" do
-          it "is true" do
-            value = "foobarbaz"
-            search = {'f', 'b', 'z'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_true
-          end
-        end
-
-        context "against one matching character" do
-          it "is false" do
-            value = "foobarbaz"
-            search = {'f', 'c', 'd'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against no matching characters" do
-          it "is false" do
-            value = "foobarbaz"
-            search = {'c', 'd', 'e'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against a matching string and character" do
-          it "is true" do
-            value = "foobarbaz"
-            search = {"foo", 'z'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_true
-          end
-        end
-
-        context "against a matching string and non-matching character" do
-          it "is false" do
-            value = "foobarbaz"
-            search = {"foo", 'c'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against a non-matching string and matching character" do
-          it "is false" do
-            value = "foobarbaz"
-            search = {"qux", 'f'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against a non-matching string and character" do
-          it "is false" do
-            value = "foobarbaz"
-            search = {"qux", 'c'}
-            partial = new_partial(value)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-      end
-    end
-
-    context "with an Enumberable" do
-      context "one argument" do
-        context "against an equal value" do
-          it "is true" do
-            array = %i[a b c]
-            search = :b
-            partial = new_partial(array)
-            matcher = Spectator::Matchers::ContainMatcher.new({search})
-            matcher.match?(partial).should be_true
-          end
-
-          context "at the beginning" do
-            it "is true" do
-              array = %i[a b c]
-              search = :a
-              partial = new_partial(array)
-              matcher = Spectator::Matchers::ContainMatcher.new({search})
-              matcher.match?(partial).should be_true
-            end
-          end
-
-          context "at the end" do
-            it "is true" do
-              array = %i[a b c]
-              search = :c
-              partial = new_partial(array)
-              matcher = Spectator::Matchers::ContainMatcher.new({search})
-              matcher.match?(partial).should be_true
-            end
-          end
-        end
-
-        context "against a different value" do
-          it "is false" do
-            array = %i[a b c]
-            search = :z
-            partial = new_partial(array)
-            matcher = Spectator::Matchers::ContainMatcher.new({search})
-            matcher.match?(partial).should be_false
-          end
-        end
-      end
-
-      context "multiple arguments" do
-        context "against equal values" do
-          it "is true" do
-            array = %i[a b c]
-            search = {:a, :b}
-            partial = new_partial(array)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_true
-          end
-        end
-
-        context "against one equal value" do
-          it "is false" do
-            array = %i[a b c]
-            search = {:a, :d}
-            partial = new_partial(array)
-            matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
-          end
-        end
-
-        context "against no equal values" do
-          it "is false" do
+      describe "#values" do
+        describe "subset" do
+          it "is the expected set" do
             array = %i[a b c]
             search = {:d, :e}
             partial = new_partial(array)
             matcher = Spectator::Matchers::ContainMatcher.new(search)
-            matcher.match?(partial).should be_false
+            match_data = matcher.match(partial)
+            match_data.values[:subset].should eq(search)
+          end
+        end
+
+        describe "superset" do
+          it "is the actual set" do
+            array = %i[a b c]
+            search = {:d, :e}
+            partial = new_partial(array)
+            matcher = Spectator::Matchers::ContainMatcher.new(search)
+            match_data = matcher.match(partial)
+            match_data.values[:superset].should eq(array)
+          end
+        end
+      end
+
+      describe "#message" do
+        it "contains the actual label" do
+          value = "foobar"
+          search = "baz"
+          label = "everything"
+          partial = new_partial(value, label)
+          matcher = Spectator::Matchers::ContainMatcher.new({search})
+          match_data = matcher.match(partial)
+          match_data.message.should contain(label)
+        end
+
+        it "contains the expected label" do
+          value = "foobar"
+          search = "baz"
+          label = "everything"
+          partial = new_partial(value)
+          matcher = Spectator::Matchers::ContainMatcher.new({search}, label)
+          match_data = matcher.match(partial)
+          match_data.message.should contain(label)
+        end
+
+        context "when expected label is omitted" do
+          it "contains stringified form of expected value" do
+            value = "foobar"
+            search = "baz"
+            partial = new_partial(value)
+            matcher = Spectator::Matchers::ContainMatcher.new({search})
+            match_data = matcher.match(partial)
+            match_data.message.should contain(search)
+          end
+        end
+      end
+
+      describe "#negated_message" do
+        it "contains the actual label" do
+          value = "foobar"
+          search = "baz"
+          label = "everything"
+          partial = new_partial(value, label)
+          matcher = Spectator::Matchers::ContainMatcher.new({search})
+          match_data = matcher.match(partial)
+          match_data.negated_message.should contain(label)
+        end
+
+        it "contains the expected label" do
+          value = "foobar"
+          search = "baz"
+          label = "everything"
+          partial = new_partial(value)
+          matcher = Spectator::Matchers::ContainMatcher.new({search}, label)
+          match_data = matcher.match(partial)
+          match_data.negated_message.should contain(label)
+        end
+
+        context "when expected label is omitted" do
+          it "contains stringified form of expected value" do
+            value = "foobar"
+            search = "baz"
+            partial = new_partial(value)
+            matcher = Spectator::Matchers::ContainMatcher.new({search})
+            match_data = matcher.match(partial)
+            match_data.negated_message.should contain(search)
           end
         end
       end
     end
   end
-
-  describe "#message" do
-    it "contains the actual label" do
-      value = "foobar"
-      search = "baz"
-      label = "everything"
-      partial = new_partial(value, label)
-      matcher = Spectator::Matchers::ContainMatcher.new({search})
-      matcher.message(partial).should contain(label)
-    end
-
-    it "contains the expected label" do
-      value = "foobar"
-      search = "baz"
-      label = "everything"
-      partial = new_partial(value)
-      matcher = Spectator::Matchers::ContainMatcher.new({search}, label)
-      matcher.message(partial).should contain(label)
-    end
-
-    context "when expected label is omitted" do
-      it "contains stringified form of expected value" do
-        value = "foobar"
-        search = "baz"
-        partial = new_partial(value)
-        matcher = Spectator::Matchers::ContainMatcher.new({search})
-        matcher.message(partial).should contain(search)
-      end
-    end
-  end
-
-  describe "#negated_message" do
-    it "contains the actual label" do
-      value = "foobar"
-      search = "baz"
-      label = "everything"
-      partial = new_partial(value, label)
-      matcher = Spectator::Matchers::ContainMatcher.new({search})
-      matcher.negated_message(partial).should contain(label)
-    end
-
-    it "contains the expected label" do
-      value = "foobar"
-      search = "baz"
-      label = "everything"
-      partial = new_partial(value)
-      matcher = Spectator::Matchers::ContainMatcher.new({search}, label)
-      matcher.negated_message(partial).should contain(label)
-    end
-
-    context "when expected label is omitted" do
-      it "contains stringified form of expected value" do
-        value = "foobar"
-        search = "baz"
-        partial = new_partial(value)
-        matcher = Spectator::Matchers::ContainMatcher.new({search})
-        matcher.negated_message(partial).should contain(search)
-      end
-    end
-  end
 end
diff --git a/src/spectator/matchers/contain_matcher.cr b/src/spectator/matchers/contain_matcher.cr
index b1783df..1f769b0 100644
--- a/src/spectator/matchers/contain_matcher.cr
+++ b/src/spectator/matchers/contain_matcher.cr
@@ -5,29 +5,45 @@ module Spectator::Matchers
   # The values are checked with the `includes?` method.
   struct ContainMatcher(ExpectedType) < ValueMatcher(ExpectedType)
     # Determines whether the matcher is satisfied with the value given to it.
-    # True is returned if the match was successful, false otherwise.
-    def match?(partial)
+    private def match?(actual)
       expected.all? do |item|
-        partial.actual.includes?(item)
+        actual.includes?(item)
       end
     end
 
     # Determines whether the matcher is satisfied with the partial given to it.
     # `MatchData` is returned that contains information about the match.
-    def match(partial) : MatchData
-      raise NotImplementedError.new("#match")
+    def match(partial)
+      values = ExpectedActual.new(partial, self)
+      MatchData.new(match?(values.actual), values)
     end
 
-    # Describes the condition that satisfies the matcher.
-    # This is informational and displayed to the end-user.
-    def message(partial)
-      "Expected #{partial.label} to contain #{label}"
-    end
+    # Match data specific to this matcher.
+    private struct MatchData(ExpectedType, ActualType) < MatchData
+      # Creates the match data.
+      def initialize(matched, @values : ExpectedActual(ExpectedType, ActualType))
+        super(matched)
+      end
 
-    # Describes the condition that won't satsify the matcher.
-    # This is informational and displayed to the end-user.
-    def negated_message(partial)
-      "Expected #{partial.label} to not contain #{label}"
+      # Information about the match.
+      def values
+        {
+          subset:   @values.expected,
+          superset: @values.actual,
+        }
+      end
+
+      # Describes the condition that satisfies the matcher.
+      # This is informational and displayed to the end-user.
+      def message
+        "#{@values.actual_label} contains #{@values.expected_label}"
+      end
+
+      # Describes the condition that won't satsify the matcher.
+      # This is informational and displayed to the end-user.
+      def negated_message
+        "#{@values.actual_label} does not contain #{@values.expected_label}"
+      end
     end
   end
 end