diff --git a/src/spectator.cr b/src/spectator.cr
index a2df911..5391a78 100644
--- a/src/spectator.cr
+++ b/src/spectator.cr
@@ -91,8 +91,9 @@ module Spectator
 
   # Builds the tests and runs the framework.
   private def run
-    # Build the test spec and run it.
-    spec = ::Spectator::DSL::Builder.build
+    # Build the spec and run it.
+    # DSL::Builder.config = config # TODO: Set config.
+    spec = DSL::Builder.build
     spec.run
     true
   rescue ex
diff --git a/src/spectator/config_builder.cr b/src/spectator/config_builder.cr
index d65ffc1..582edaf 100644
--- a/src/spectator/config_builder.cr
+++ b/src/spectator/config_builder.cr
@@ -1,3 +1,7 @@
+require "./composite_example_filter"
+require "./example_filter"
+require "./null_example_filter"
+
 module Spectator
   # Mutable configuration used to produce a final configuration.
   # Use the setters in this class to incrementally build a configuration.
diff --git a/src/spectator/dsl/builder.cr b/src/spectator/dsl/builder.cr
index 638b39d..dc4647c 100644
--- a/src/spectator/dsl/builder.cr
+++ b/src/spectator/dsl/builder.cr
@@ -35,6 +35,13 @@ module Spectator::DSL
       @@builder.add_example(*args, &block)
     end
 
+    # Sets the configuration of the spec.
+    #
+    # See `Spec::Builder#config=` for usage details.
+    def config=(config)
+      @@builder.config = config
+    end
+
     # Constructs the test spec.
     # Returns the spec instance.
     #
diff --git a/src/spectator/spec.cr b/src/spectator/spec.cr
index 17218f9..a1dfa5c 100644
--- a/src/spectator/spec.cr
+++ b/src/spectator/spec.cr
@@ -1,3 +1,4 @@
+require "./config"
 require "./example"
 require "./example_group"
 require "./example_iterator"
@@ -5,14 +6,28 @@ require "./example_iterator"
 module Spectator
   # Contains examples to be tested.
   class Spec
-    def initialize(@root : ExampleGroup)
+    def initialize(@root : ExampleGroup, @config : Config)
     end
 
     def run
-      examples = ExampleIterator.new(@root).to_a
       Runner.new(examples).run
     end
 
+    # Generates a list of examples to run.
+    # The order of the examples are also sorted based on the configuration.
+    private def examples
+      ExampleIterator.new(@root).to_a.tap do |examples|
+        if @config.randomize?
+          random = if (seed = @config.random_seed)
+            Random.new(seed)
+          else
+            Random.new
+          end
+          examples.shuffle!(random)
+        end
+      end
+    end
+
     private struct Runner
       def initialize(@examples : Array(Example))
       end
diff --git a/src/spectator/spec_builder.cr b/src/spectator/spec_builder.cr
index 09c81a0..54f8ed6 100644
--- a/src/spectator/spec_builder.cr
+++ b/src/spectator/spec_builder.cr
@@ -1,3 +1,5 @@
+require "./config"
+require "./config_builder"
 require "./example"
 require "./example_context_method"
 require "./example_group"
@@ -17,6 +19,9 @@ module Spectator
     # New examples should be added to the current group.
     @group_stack : Deque(ExampleGroup)
 
+    # Configuration for the spec.
+    @config : Config?
+
     # Creates a new spec builder.
     # A root group is pushed onto the group stack.
     def initialize
@@ -82,6 +87,12 @@ module Spectator
       # The example is added to the current group by `Example` initializer.
     end
 
+    # Sets the configuration of the spec.
+    # This configuration controls how examples run.
+    def config=(config)
+      @config = config
+    end
+
     # Constructs the test spec.
     # Returns the spec instance.
     #
@@ -90,7 +101,7 @@ module Spectator
     def build : Spec
       raise "Mismatched start and end groups" unless root?
 
-      Spec.new(root_group)
+      Spec.new(root_group, config)
     end
 
     # Checks if the current group is the root group.
@@ -108,5 +119,11 @@ module Spectator
     private def current_group
       @group_stack.last
     end
+
+    # Retrieves the configuration.
+    # If one wasn't previously set, a default configuration is used.
+    private def config
+      @config || ConfigBuilder.new.build
+    end
   end
 end