diff --git a/src/spectator/expectations/expectation_partial.cr b/src/spectator/expectations/expectation_partial.cr
index 4bb7813..698b072 100644
--- a/src/spectator/expectations/expectation_partial.cr
+++ b/src/spectator/expectations/expectation_partial.cr
@@ -45,6 +45,24 @@ module Spectator::Expectations
       to_not(matcher)
     end
 
+    # Asserts that some criteria defined by the matcher is eventually satisfied.
+    # The expectation is checked after the example finishes and all hooks have run.
+    def to_eventually(matcher) : Nil
+      Harness.current.defer { to(matcher) }
+    end
+
+    # Asserts that some criteria defined by the matcher is never satisfied.
+    # The expectation is checked after the example finishes and all hooks have run.
+    def to_never(matcher) : Nil
+      Harness.current.defer { to_not(matcher) }
+    end
+
+    # ditto
+    @[AlwaysInline]
+    def never_to(matcher) : Nil
+      to_never(matcher)
+    end
+
     # Reports an expectation to the current harness.
     private def report(match_data : Matchers::MatchData)
       expectation = Expectation.new(match_data, @source)
diff --git a/src/spectator/harness.cr b/src/spectator/harness.cr
index 537bbf2..e197e2e 100644
--- a/src/spectator/harness.cr
+++ b/src/spectator/harness.cr
@@ -55,11 +55,23 @@ module Spectator
       @reporter.expectations
     end
 
+    # Marks a block of code to run later.
+    def defer(&block : ->) : Nil
+      @deferred << block
+    end
+
+    # Runs all deferred blocks.
+    def run_deferred : Nil
+      @deferred.each(&.call)
+      @deferred.clear
+    end
+
     # Creates a new harness.
     # The example the harness is for should be passed in.
     private def initialize(@example)
       @reporter = Expectations::ExpectationReporter.new
-      @mocks = Mocks::Registry.new(@example.group.context)
+      @mocks    = Mocks::Registry.new(@example.group.context)
+      @deferred = Deque(->).new
     end
   end
 end
diff --git a/src/spectator/runnable_example.cr b/src/spectator/runnable_example.cr
index d981689..9bbbbed 100644
--- a/src/spectator/runnable_example.cr
+++ b/src/spectator/runnable_example.cr
@@ -20,6 +20,7 @@ module Spectator
         context.run_before_hooks(self)
         run_example(result)
         context.run_after_hooks(self)
+        run_deferred(result)
       end
     end
 
@@ -40,6 +41,17 @@ module Spectator
       end
     end
 
+    # Runs the deferred blocks of code and captures the result.
+    private def run_deferred(result)
+      result.elapsed += Time.measure do
+        begin
+          Harness.current.run_deferred
+        rescue ex # Catch all errors and handle them later.
+          result.error = ex
+        end
+      end
+    end
+
     # Creates a result instance from captured result information.
     private def translate_result(result, expectations)
       case (error = result.error)
diff --git a/src/spectator/should.cr b/src/spectator/should.cr
index de75c85..b8cda4a 100644
--- a/src/spectator/should.cr
+++ b/src/spectator/should.cr
@@ -16,7 +16,7 @@ class Object
   # ```
   # require "spectator/should"
   # ```
-  def should(matcher : ::Spectator::Matchers::Matcher)
+  def should(matcher)
     # First argument of the `Expectation` initializer is the expression label.
     # However, since this isn't a macro and we can't "look behind" this method call
     # to see what it was invoked on, the argument is an empty string.
@@ -28,17 +28,29 @@ class Object
 
   # Works the same as `#should` except the condition is inverted.
   # When `#should` succeeds, this method will fail, and vice-versa.
-  def should_not(matcher : ::Spectator::Matchers::Matcher)
+  def should_not(matcher)
     actual = ::Spectator::TestValue.new(self)
     source = ::Spectator::Source.new(__FILE__, __LINE__)
     ::Spectator::Expectations::ExpectationPartial.new(actual, source).to_not(matcher)
   end
+
+  # Works the same as `#should` except that the condition check is postphoned.
+  # The expectation is checked after the example finishes and all hooks have run.
+  def should_eventually(matcher)
+    ::Spectator::Harness.current.defer { should(matcher) }
+  end
+
+  # Works the same as `#should_not` except that the condition check is postphoned.
+  # The expectation is checked after the example finishes and all hooks have run.
+  def should_never(matcher)
+    ::Spectator::Harness.current.defer { should_not(matcher) }
+  end
 end
 
 struct Proc(*T, R)
   # Extension method to create an expectation for a block of code (proc).
   # Depending on the matcher, the proc may be executed multiple times.
-  def should(matcher : ::Spectator::Matchers::Matcher)
+  def should(matcher)
     actual = ::Spectator::TestBlock.new(self)
     source = ::Spectator::Source.new(__FILE__, __LINE__)
     ::Spectator::Expectations::ExpectationPartial.new(actual, source).to(matcher)
@@ -46,7 +58,7 @@ struct Proc(*T, R)
 
   # Works the same as `#should` except the condition is inverted.
   # When `#should` succeeds, this method will fail, and vice-versa.
-  def should_not(matcher : ::Spectator::Matchers::Matcher)
+  def should_not(matcher)
     actual = ::Spectator::TestBlock.new(self)
     source = ::Spectator::Source.new(__FILE__, __LINE__)
     ::Spectator::Expectations::BlockExpectationPartial.new(actual, source).to_not(matcher)