diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright (c) 2013, Nathan "Taneb" van Doorn
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Nathan "Taneb" van Doorn nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/groups.cabal b/groups.cabal
new file mode 100644
--- /dev/null
+++ b/groups.cabal
@@ -0,0 +1,19 @@
+name:                groups
+version:             0.1
+synopsis:            Haskell 98 groups
+description:         
+  Haskell 98 groups. A group is a monoid with invertibility.
+license:             BSD3
+license-file:        LICENSE
+author:              Nathan "Taneb" van Doorn
+maintainer:          nvd1234@gmail.com
+copyright:           Copyright (C) 2013 Nathan van Doorn
+category:            Algebra, Data, Math
+build-type:          Simple
+cabal-version:       >=1.8
+
+library
+  exposed-modules:     Data.Group
+  -- other-modules:       
+  build-depends:       base ==4.5.*
+  hs-source-dirs:      src
diff --git a/src/Data/Group.hs b/src/Data/Group.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Group.hs
@@ -0,0 +1,36 @@
+module Data.Group where
+
+import Data.Monoid
+
+-- |A 'Group' is a 'Monoid' plus a function, 'invert', such that: 
+--
+-- @a <> invert a == mempty@
+class Monoid m => Group m where
+  invert :: m -> m
+  
+instance Group () where
+  invert () = ()
+
+instance Num a => Group (Sum a) where
+  invert = Sum . negate . getSum
+  {-# INLINE invert #-}
+  
+instance Fractional a => Group (Product a) where
+  invert = Product . recip . getProduct
+  {-# INLINE invert #-}
+
+instance Group a => Group (Dual a) where
+  invert = Dual . invert . getDual
+  {-# INLINE invert #-}
+  
+instance (Group a, Group b) => Group (a, b) where
+  invert (a, b) = (invert a, invert b)
+  
+instance (Group a, Group b, Group c) => Group (a, b, c) where
+  invert (a, b, c) = (invert a, invert b, invert c)
+
+instance (Group a, Group b, Group c, Group d) => Group (a, b, c, d) where
+  invert (a, b, c, d) = (invert a, invert b, invert c, invert d)
+
+instance (Group a, Group b, Group c, Group d, Group e) => Group (a, b, c, d, e) where
+  invert (a, b, c, d, e) = (invert a, invert b, invert c, invert d, invert e)