diff --git a/sets.cabal b/sets.cabal
--- a/sets.cabal
+++ b/sets.cabal
@@ -1,5 +1,5 @@
 Name:                   sets
-Version:                0.0.2.1
+Version:                0.0.2.2
 Author:                 Athan Clark <athan.clark@gmail.com>
 Maintainer:             Athan Clark <athan.clark@gmail.com>
 License:                MIT
diff --git a/src/Data/Set/Class.hs b/src/Data/Set/Class.hs
--- a/src/Data/Set/Class.hs
+++ b/src/Data/Set/Class.hs
@@ -54,8 +54,9 @@
 import qualified Data.Set.Ordered.Unique.Finite as OUF
 
 
-newtype Union a = Union {unUnion :: a}
+newtype Union a        = Union {unUnion :: a}
 newtype Intersection a = Intersection {unIntersection :: a}
+newtype XUnion a       = XUnion {unXUnion :: a}
 
 class HasUnion s where
   union :: s -> s -> s
@@ -69,6 +70,10 @@
 instance HasUnion s => Commutative (Union s) where
   commute = union
 
+instance (HasUnion s, HasEmpty s) => Monoid.Monoid (Union s) where
+  mappend = union
+  mempty = empty
+
 class HasDifference s where
   difference :: s -> s -> s
 
@@ -84,12 +89,24 @@
 instance HasIntersection s => Commutative (Intersection s) where
   commute = intersection
 
+instance (HasIntersection s, HasTotal s) => Monoid.Monoid (Intersection s) where
+  mappend = intersection
+  mempty = total
+
 class HasXUnion s where
   xunion :: s -> s -> s
 
 instance (HasUnion s, HasIntersection s, HasDifference s) => HasXUnion s where
   xunion x y = union x y `difference` intersection x y
 
+instance (HasXUnion s, HasUnion s, HasIntersection s, HasDifference s) => Commutative (XUnion s) where
+  commute = xunion
+
+instance (HasXUnion s, HasEmpty s, HasUnion s, HasIntersection s, HasDifference s) => Monoid.Monoid (XUnion s) where
+  mappend = xunion
+  mempty = empty
+
+
 class HasComplement s where
   complement :: s -> s
 
@@ -156,6 +173,19 @@
 deriving instance HasSize a              => HasSize              (Intersection a)
 deriving instance CanBeSubset a          => CanBeSubset          (Intersection a)
 deriving instance CanBeProperSubset a    => CanBeProperSubset    (Intersection a)
+deriving instance HasUnion a             => HasUnion             (XUnion a)
+deriving instance HasDifference a        => HasDifference        (XUnion a)
+deriving instance HasIntersection a      => HasIntersection      (XUnion a)
+deriving instance HasComplement a        => HasComplement        (XUnion a)
+deriving instance HasSingleton x a       => HasSingleton x       (XUnion a)
+deriving instance HasSingletonWith k x a => HasSingletonWith k x (XUnion a)
+deriving instance HasEmpty a             => HasEmpty             (XUnion a)
+deriving instance HasEmptyWith k a       => HasEmptyWith k       (XUnion a)
+deriving instance HasTotal a             => HasTotal             (XUnion a)
+deriving instance HasTotalWith k a       => HasTotalWith  k      (XUnion a)
+deriving instance HasSize a              => HasSize              (XUnion a)
+deriving instance CanBeSubset a          => CanBeSubset          (XUnion a)
+deriving instance CanBeProperSubset a    => CanBeProperSubset    (XUnion a)
 
 
 -- Data.Set