diff --git a/lib/oga.rb b/lib/oga.rb
index 8eee85b..414dc2a 100644
--- a/lib/oga.rb
+++ b/lib/oga.rb
@@ -8,6 +8,8 @@ require_relative 'oga/oga'
 require_relative 'oga/lru'
 require_relative 'oga/entity_decoder'
 require_relative 'oga/node_name_set'
+require_relative 'oga/blacklist'
+require_relative 'oga/whitelist'
 
 # Load these first so that the native extensions don't have to define the
 # Oga::XML namespace.
diff --git a/lib/oga/blacklist.rb b/lib/oga/blacklist.rb
new file mode 100644
index 0000000..f6013bb
--- /dev/null
+++ b/lib/oga/blacklist.rb
@@ -0,0 +1,40 @@
+module Oga
+  ##
+  # @api private
+  #
+  class Blacklist
+    # @return [Set]
+    attr_reader :names
+
+    ##
+    # @param [Array] names
+    #
+    def initialize(names)
+      @names = Set.new(names + names.map(&:upcase))
+    end
+
+    ##
+    # @yieldparam [String]
+    #
+    def each
+      names.each do |value|
+        yield value
+      end
+    end
+
+    ##
+    # @return [TrueClass|FalseClass]
+    #
+    def allow?(name)
+      return !names.include?(name)
+    end
+
+    ##
+    # @param [Oga::Blacklist] other
+    # @return [Oga::Blacklist]
+    #
+    def +(other)
+      return self.class.new(names + other.names)
+    end
+  end # Blacklist
+end # Oga
diff --git a/lib/oga/whitelist.rb b/lib/oga/whitelist.rb
new file mode 100644
index 0000000..8a76670
--- /dev/null
+++ b/lib/oga/whitelist.rb
@@ -0,0 +1,20 @@
+module Oga
+  ##
+  # @api private
+  #
+  class Whitelist < Blacklist
+    ##
+    # @return [TrueClass|FalseClass]
+    #
+    def allow?(name)
+      return names.include?(name)
+    end
+
+    ##
+    # @return [Oga::Blacklist]
+    #
+    def to_blacklist
+      return Blacklist.new(names)
+    end
+  end # Whitelist
+end # Oga
diff --git a/spec/oga/blacklist_spec.rb b/spec/oga/blacklist_spec.rb
new file mode 100644
index 0000000..759b519
--- /dev/null
+++ b/spec/oga/blacklist_spec.rb
@@ -0,0 +1,39 @@
+require 'spec_helper'
+
+describe Oga::Blacklist do
+  describe '#each' do
+    it 'yields each value in the list' do
+      list = described_class.new(%w{foo bar})
+
+      expect { |block| list.each(&block) }
+        .to yield_successive_args('foo', 'bar', 'FOO', 'BAR')
+    end
+  end
+
+  describe '#allow?' do
+    it 'returns true for a name not in the list' do
+      list = described_class.new(%w{foo})
+
+      list.allow?('bar').should == true
+      list.allow?('BAR').should == true
+    end
+
+    it 'returns false for a name in the list' do
+      list = described_class.new(%w{foo})
+
+      list.allow?('foo').should == false
+      list.allow?('FOO').should == false
+    end
+  end
+
+  describe '#+' do
+    it 'returns a new Blacklist' do
+      list1 = described_class.new(%w{foo})
+      list2 = described_class.new(%w{bar})
+      list3 = list1 + list2
+
+      list3.should be_an_instance_of(described_class)
+      list3.names.to_a.should == %w{foo FOO bar BAR}
+    end
+  end
+end
diff --git a/spec/oga/whitelist_spec.rb b/spec/oga/whitelist_spec.rb
new file mode 100644
index 0000000..85d5e45
--- /dev/null
+++ b/spec/oga/whitelist_spec.rb
@@ -0,0 +1,49 @@
+require 'spec_helper'
+
+describe Oga::Whitelist do
+  describe '#each' do
+    it 'yields each value in the list' do
+      list = described_class.new(%w{foo bar})
+
+      expect { |block| list.each(&block) }
+        .to yield_successive_args('foo', 'bar', 'FOO', 'BAR')
+    end
+  end
+
+  describe '#allow?' do
+    it 'returns false for a name not in the list' do
+      list = described_class.new(%w{foo})
+
+      list.allow?('bar').should == false
+      list.allow?('BAR').should == false
+    end
+
+    it 'returns true for a name in the list' do
+      list = described_class.new(%w{foo})
+
+      list.allow?('foo').should == true
+      list.allow?('FOO').should == true
+    end
+  end
+
+  describe '#+' do
+    it 'returns a new Blacklist' do
+      list1 = described_class.new(%w{foo})
+      list2 = described_class.new(%w{bar})
+      list3 = list1 + list2
+
+      list3.should be_an_instance_of(described_class)
+      list3.names.to_a.should == %w{foo FOO bar BAR}
+    end
+  end
+
+  describe '#to_blacklist' do
+    it 'returns a Blacklist containing the same values' do
+      whitelist = described_class.new(%w{foo})
+      blacklist = whitelist.to_blacklist
+
+      blacklist.should be_an_instance_of(Oga::Blacklist)
+      blacklist.names.should == whitelist.names
+    end
+  end
+end