diff --git a/src/spectator/formatting/document_formatter.cr b/src/spectator/formatting/document_formatter.cr
index 61c298e..89099cd 100644
--- a/src/spectator/formatting/document_formatter.cr
+++ b/src/spectator/formatting/document_formatter.cr
@@ -1,6 +1,93 @@
+require "../label"
 require "./formatter"
+require "./summary"
 
 module Spectator::Formatting
+  # Produces an indented document-style output.
+  # Each nested group of examples increases the indent.
+  # Example names are output in a color based on their result.
   class DocumentFormatter < Formatter
+    include Summary
+
+    # Whitespace count per indent.
+    private INDENT_AMOUNT = 2
+
+    # Output stream to write results to.
+    private getter io
+
+    @previous_hierarchy = [] of Label
+
+    # Creates the formatter.
+    # By default, output is sent to STDOUT.
+    def initialize(@io : IO = STDOUT)
+    end
+
+    # Invoked just before an example runs.
+    # Prints the example group hierarchy if it changed.
+    def example_started(notification)
+      hierarchy = group_hierarchy(notification.example)
+      tuple = hierarchy_diff(@previous_hierarchy, hierarchy)
+      print_sub_hierarchy(*tuple)
+      @previous_hierarchy = hierarchy
+    end
+
+    # Invoked after an example completes successfully.
+    # Produces a successful example line.
+    def example_passed(notification)
+      indent = @previous_hierarchy.size * INDENT_AMOUNT
+      indent.times { @io << ' ' }
+      @io.puts notification.example.name.colorize(:green)
+    end
+
+    # Invoked after an example is skipped or marked as pending.
+    # Produces a pending example line.
+    def example_pending(notification)
+      indent = @previous_hierarchy.size * INDENT_AMOUNT
+      indent.times { @io << ' ' }
+      @io.puts notification.example.name.colorize(:yellow)
+    end
+
+    # Invoked after an example fails.
+    # Produces a failure example line.
+    def example_failed(notification)
+      indent = @previous_hierarchy.size * INDENT_AMOUNT
+      indent.times { @io << ' ' }
+      @io.puts notification.example.name.colorize(:red)
+    end
+
+    # Invoked after an example fails from an unexpected error.
+    # Produces a failure example line.
+    def example_error(notification)
+      example_failed(notification)
+    end
+
+    # Produces a list of groups making up the hierarchy for an example.
+    private def group_hierarchy(example)
+      hierarchy = [] of Label
+      group = example.group?
+      while group && (parent = group.group?)
+        hierarchy << group.name
+        group = parent
+      end
+      hierarchy.reverse
+    end
+
+    # Generates a difference between two hierarchies.
+    private def hierarchy_diff(first, second)
+      index = -1
+      diff = second.skip_while do |group|
+        index += 1
+        first.size > index && first[index] == group
+      end
+      {index, diff}
+    end
+
+    # Displays an indented hierarchy starting partially into the whole hierarchy.
+    private def print_sub_hierarchy(start_index, sub_hierarchy)
+      sub_hierarchy.each_with_index(start_index) do |name, index|
+        (index * INDENT_AMOUNT).times { @io << ' ' }
+        @io.puts name
+      end
+    end
   end
 end