diff --git a/CompState.hs b/CompState.hs
index 9e44e1d..72e2f36 100644
--- a/CompState.hs
+++ b/CompState.hs
@@ -35,12 +35,17 @@ data CompMode = ModeParse | ModeCompile | ModePostC
 -- | Backends that Tock can use.
 data CompBackend = BackendC | BackendCPPCSP
   deriving (Show, Data, Typeable)
+  
+-- | Frontends that Tock can use.
+data CompFrontend = FrontendOccam21 | FrontendRain
+  deriving (Show, Data, Typeable)  
 
 -- | State necessary for compilation.
 data CompState = CompState {
     -- Set by Main (from command-line options)
     csMode :: CompMode,
     csBackend :: CompBackend,
+    csFrontend :: CompFrontend,
     csVerboseLevel :: Int,
     csOutputFile :: String,
 
@@ -76,6 +81,7 @@ emptyState :: CompState
 emptyState = CompState {
     csMode = ModeCompile,
     csBackend = BackendC,
+    csFrontend = FrontendOccam21,
     csVerboseLevel = 0,
     csOutputFile = "-",
 
diff --git a/Main.hs b/Main.hs
index e160c6f..ffc2cdf 100644
--- a/Main.hs
+++ b/Main.hs
@@ -35,6 +35,8 @@ import GenerateCPPCSP
 import Parse
 import Pass
 import PrettyShow
+import RainParse
+import RainPasses
 import SimplifyExprs
 import SimplifyProcs
 import SimplifyTypes
@@ -54,6 +56,7 @@ options :: [OptDescr OptFunc]
 options =
   [ Option [] ["mode"] (ReqArg optMode "MODE") "select mode (options: parse, compile, post-c)"
   , Option [] ["backend"] (ReqArg optBackend "BACKEND") "code-generating backend (options: c, cppcsp)"
+  , Option [] ["frontend"] (ReqArg optFrontend "FRONTEND") "language frontend (options: occam21, rain)"
   , Option ['v'] ["verbose"] (NoArg $ optVerbose) "be more verbose (use multiple times for more detail)"
   , Option ['o'] ["output"] (ReqArg optOutput "FILE") "output file (default \"-\")"
   ]
@@ -75,6 +78,14 @@ optBackend s ps
             _ -> dieIO $ "Unknown backend: " ++ s
           return $ ps { csBackend = backend }
 
+optFrontend :: String -> OptFunc
+optFrontend s ps 
+    =  do frontend <- case s of
+            "occam21" -> return FrontendOccam21
+            "rain" -> return FrontendRain
+            _ -> dieIO $ "Unknown frontend: " ++ s
+          return $ ps { csFrontend = frontend }
+
 optVerbose :: OptFunc
 optVerbose ps = return $ ps { csVerboseLevel = csVerboseLevel ps + 1 }
 
@@ -136,7 +147,9 @@ compile fn
 
         debug "{{{ Parse"
         progress "Parse"
-        ast1 <- parseProgram fn
+        ast1 <- case csFrontend optsPS of
+          FrontendOccam21 -> parseProgram fn
+          FrontendRain -> parseRainProgram fn
         debugAST ast1
         debug "}}}"
 
@@ -147,7 +160,10 @@ compile fn
             ModeParse -> return $ show ast1
             ModeCompile ->
               do progress "Passes:"
-                 ast2 <- (runPasses passes) ast1
+                 ast2 <- case csFrontend optsPS of                   
+                   FrontendOccam21 -> (runPasses passes) ast1
+                   --Run the rain passes, then all the normal occam passes too:
+                   FrontendRain -> ((runPasses rainPasses) ast1) >>= (runPasses passes)
 
                  debug "{{{ Generate code"
                  let generator
diff --git a/RainParse.hs b/RainParse.hs
index 5715f0d..3477ded 100644
--- a/RainParse.hs
+++ b/RainParse.hs
@@ -269,4 +269,30 @@ statement
            }    
     <|> do { m <- md ; sSemiColon ; return $ A.Skip m}
     <?> "statement"
---TODO the "each" statements
+
+rainSourceFile :: RainParser (A.Process, CompState)
+rainSourceFile
+    =   do whiteSpace
+           --TODO change from stattement to declaration (once the latter is written):
+           p <- statement
+           s <- getState
+           return (p, s)
+
+-- | Parse a file with the given production.
+-- This is copied from Parse.hs (because OccParser is about to be changed to not be the same as RainParser):
+parseFile :: Monad m => String -> RainParser t -> CompState -> m t
+parseFile file prod ps
+    =  do let source = case Map.lookup file (csSourceFiles ps) of
+                         Just s -> s
+                         Nothing -> dieIO $ "Failed to preload file: " ++ show file
+          let ps' = ps { csLoadedFiles = file : csLoadedFiles ps }
+          case runParser prod ps' file source of
+            Left err -> dieIO $ "Parse error: " ++ show err
+            Right r -> return r
+
+parseRainProgram :: String -> PassM A.Process
+parseRainProgram file
+    =  do ps <- get
+          (p, ps') <- parseFile file rainSourceFile ps
+          put ps'
+          return p
diff --git a/RainPasses.hs b/RainPasses.hs
index 41d3242..da0c54f 100644
--- a/RainPasses.hs
+++ b/RainPasses.hs
@@ -26,10 +26,8 @@ import Types
 import CompState
 import Errors
 
-rainPasses :: A.Process -> PassM A.Process
-rainPasses = runPasses passes
-  where
-    passes = 
+rainPasses :: [(String,Pass)]
+rainPasses = 
      [ ("Uniquify variable declarations and resolve variable names",uniquifyAndResolveVars)
        ,("Record declared name types in dictionary",recordDeclNameTypes)
        ,("Record inferred name types in dictionary",recordInfNameTypes)