diff --git a/Test/HTTP.hs b/Test/HTTP.hs
--- a/Test/HTTP.hs
+++ b/Test/HTTP.hs
@@ -1,4 +1,4 @@
-module Test.HTTP (httpTest, session, get, getJSON, postForm, assert, debug, Program, Session) where
+module Test.HTTP (httpTest, session, get, getJSON, withJSON, postForm, assert, assertEq, assertParse, debug, Program, Session) where
 
 import Network.Curl hiding (curlGetString)
 
@@ -16,6 +16,7 @@
 import Data.Maybe
 import GHC.Conc
 import qualified Data.Aeson as Ae
+import Data.Aeson.Types (Parser, parseEither)
 import Safe (readMay)
 import System.Environment
 import System.Exit
@@ -27,13 +28,10 @@
 type Program = ReaderT (TVar [Results]) IO
 
 data SessionState = SessionState { sessionResults :: Results,
-                               sessionBaseUrl :: String,
-                               sessionCurl :: Curl }
-
---what we really want
---type Session = EitherT String (State.StateT SessionState IO)
+                                   sessionBaseUrl :: String,
+                                   sessionCurl :: Curl }
 
-type Session = State.StateT SessionState IO
+type Session a = State.StateT SessionState (ErrorT String IO) a
 
 type Results = [(String, Maybe String)]
 
@@ -59,17 +57,26 @@
 session :: String -- ^ Session name (used for logging failures)
         -> String -- ^ Base URL
         -> Session () -- ^ the actions and assertions that define the session
-        ->  Program ()
+        -> Program ()
 session sessionName baseURL m = do
    c <- liftIO $ initialize
    let state0 = SessionState [] baseURL c
    liftIO $ setopts c [CurlCookieJar (sessionName++"_cookies"), 
                        CurlFollowLocation True]
-   SessionState res _ _ <- liftIO $ State.execStateT m state0
-   res_tv <- ask
-   liftIO $ atomically $ do 
-       others <- readTVar res_tv
-       writeTVar res_tv $ others ++ [res]
+   res <- liftIO $ runErrorT $ State.execStateT m state0
+   case res of 
+      Right (SessionState res _ _) -> do
+         res_tv <- ask
+         liftIO $ atomically $ do 
+            others <- readTVar res_tv
+            writeTVar res_tv $ others ++ [reverse res]
+      Left err -> do
+         res_tv <- ask
+         liftIO $ atomically $ do 
+            others <- readTVar res_tv
+            writeTVar res_tv $ others ++ 
+                               [[(sessionName, 
+                                 Just $ sessionName ++ " session failure:" ++err)]]
 
 -- | GET a web page as a String
 get :: String -- ^ URL
@@ -87,14 +94,28 @@
 
 -- | GET a JSON value
 getJSON :: Ae.FromJSON a => 
-        String -- ^ URL
-        -> Session a
+           String  -- ^ URL
+           -> Session a
 getJSON url = do
   str <- get url
-  let Just x = Ae.decode' $ fromStrict $ encodeUtf8 $ T.pack str
-  return x
+  case Ae.eitherDecode' $ fromStrict $ encodeUtf8 $ T.pack str of
+    Right x -> return x
+    Left err -> throwError $  "GET "++url ++ " JSON decoding failure: "++ err
 
--- | POST a form
+
+-- | perform an action with a JSON value from a GET
+withJSON :: Ae.FromJSON a => 
+           String  -- ^ URL
+           -> (a -> Session ()) -- ^ action to perform on successfully decoded value
+           -> Session ()
+withJSON url mu = do
+  str <- get url
+  case Ae.eitherDecode' $ fromStrict $ encodeUtf8 $ T.pack str of
+    Right x -> mu x
+    Left err -> do failTest ("GET "++url) $ "JSON decoding failure: "++ err
+                   return ()
+
+-- | Post a form
 postForm :: String -- ^ URL
          -> [(String,String)]  -- ^ form fields
          -> Session String
@@ -109,10 +130,27 @@
 assert :: String -- ^ assertion name (used for reporting failures
        -> Bool -- ^ Boolean of which we are asserting truth
        -> Session ()
-assert assName True = 
-  passTest assName
-assert assName False =
-  failTest assName "fail" 
+assert assName True = passTest assName
+assert assName False = failTest assName "fail" 
+
+-- | assert equality, for better output messages
+assertEq :: (Show a, Eq a) => String -- ^ assertion name (used for reporting failures
+       -> a  -- ^ a value
+       -> a  -- ^ what it is meant to be equal to
+       -> Session ()
+assertEq assName x y | x == y    = passTest assName
+                     | otherwise = failTest assName $ "not equal: "++show x ++" /= "++show y
+
+-- | make an assertion in the Parser monad, ofr use with JSON value
+assertParse :: String      -- ^ assertion name (used for reporting failures
+            -> Parser Bool -- ^ Boolean of which we are asserting truth
+            -> Session ()
+assertParse assName pb  =
+  case parseEither (const pb) () of
+    Left err -> failTest assName $ "parse failure: "++err
+    Right True -> passTest assName
+    Right False -> failTest assName "fail" 
+
 
 -- | Output a string to stdout if @--verbose@ is in command line arguments
 debug :: String -> Session ()
diff --git a/http-test.cabal b/http-test.cabal
--- a/http-test.cabal
+++ b/http-test.cabal
@@ -1,5 +1,5 @@
 Name:                http-test
-Version:             0.1.2
+Version:             0.1.3
 synopsis:            Test framework for HTTP APIs
 Description:         A simple framework for making assertions about the 
                      responses of HTTP servers.