diff --git a/src/Control/Abstract/Value.hs b/src/Control/Abstract/Value.hs
index 49434a1ea..50d0403d9 100644
--- a/src/Control/Abstract/Value.hs
+++ b/src/Control/Abstract/Value.hs
@@ -16,6 +16,7 @@ module Control.Abstract.Value
 , while
 , doWhile
 , forLoop
+, While(..)
 , makeNamespace
 , evaluateInScopedEnv
 , address
@@ -36,7 +37,7 @@ import Data.Abstract.Number as Number
 import Data.Abstract.Ref
 import Data.Scientific (Scientific)
 import Data.Span
-import Prologue hiding (TypeError)
+import Prologue hiding (TypeError, catchError)
 
 -- | This datum is passed into liftComparison to handle the fact that Ruby and PHP
 --   have built-in generalized-comparison ("spaceship") operators. If you want to
@@ -102,6 +103,58 @@ instance PureEffect (Boolean value) where
   handle handler (Request (AsBool v)         k) = Request (AsBool v)  (handler . k)
   handle handler (Request (Disjunction a b)  k) = Request (Disjunction (handler a) (handler b))  (handler . k)
 
+-- | The fundamental looping primitive, built on top of 'ifthenelse'.
+while :: Member (While value) effects
+  => Evaluator address value effects value -- ^ Condition
+  -> Evaluator address value effects value -- ^ Body
+  -> Evaluator address value effects value
+while (Evaluator cond) (Evaluator body) = send (While cond body)
+
+-- | Do-while loop, built on top of while.
+doWhile :: (AbstractValue address value effects, Member (Boolean value) effects)
+        => Evaluator address value effects value
+        -> Evaluator address value effects value
+        -> Evaluator address value effects value
+doWhile body cond = undefined
+
+-- | C-style for loops.
+forLoop :: ( AbstractValue address value effects
+           , Member (Boolean value) effects
+           , Member (While value) effects
+           , Member (Env address) effects
+           )
+        => Evaluator address value effects value -- ^ Initial statement
+        -> Evaluator address value effects value -- ^ Condition
+        -> Evaluator address value effects value -- ^ Increment/stepper
+        -> Evaluator address value effects value -- ^ Body
+        -> Evaluator address value effects value
+forLoop initial cond step body =
+  locally (initial *> while cond (body *> step))
+
+-- -- | The fundamental looping primitive, built on top of 'ifthenelse'.
+-- while :: (AbstractValue address value effects, Member (Boolean value) effects)
+--       => Evaluator address value effects value
+--       -> Evaluator address value effects value
+--       -> Evaluator address value effects value
+-- while cond body = loop $ \ continue -> do
+--   this <- cond
+--   ifthenelse this (body *> continue) (pure unit)
+--
+-- -- | Do-while loop, built on top of while.
+-- doWhile :: (AbstractValue address value effects, Member (Boolean value) effects)
+--         => Evaluator address value effects value
+--         -> Evaluator address value effects value
+--         -> Evaluator address value effects value
+-- doWhile body cond = loop $ \ continue -> body *> do
+--   this <- cond
+--   ifthenelse this continue (pure unit)
+
+data While value m result where
+  While :: m value -> m value -> While value m value
+
+instance PureEffect (While value) where
+  handle handler (Request (While cond body) k) = Request (While (handler cond) (handler body)) (handler . k)
+
 
 class Show value => AbstractIntro value where
   -- | Construct an abstract unit value.
@@ -210,37 +263,6 @@ class AbstractIntro value => AbstractValue address value effects where
   loop :: (Evaluator address value effects value -> Evaluator address value effects value) -> Evaluator address value effects value
 
 
--- | C-style for loops.
-forLoop :: ( AbstractValue address value effects
-           , Member (Boolean value) effects
-           , Member (Env address) effects
-           )
-        => Evaluator address value effects value -- ^ Initial statement
-        -> Evaluator address value effects value -- ^ Condition
-        -> Evaluator address value effects value -- ^ Increment/stepper
-        -> Evaluator address value effects value -- ^ Body
-        -> Evaluator address value effects value
-forLoop initial cond step body =
-  locally (initial *> while cond (body *> step))
-
--- | The fundamental looping primitive, built on top of 'ifthenelse'.
-while :: (AbstractValue address value effects, Member (Boolean value) effects)
-      => Evaluator address value effects value
-      -> Evaluator address value effects value
-      -> Evaluator address value effects value
-while cond body = loop $ \ continue -> do
-  this <- cond
-  ifthenelse this (body *> continue) (pure unit)
-
--- | Do-while loop, built on top of while.
-doWhile :: (AbstractValue address value effects, Member (Boolean value) effects)
-        => Evaluator address value effects value
-        -> Evaluator address value effects value
-        -> Evaluator address value effects value
-doWhile body cond = loop $ \ continue -> body *> do
-  this <- cond
-  ifthenelse this continue (pure unit)
-
 makeNamespace :: ( AbstractValue address value effects
                  , Member (Deref value) effects
                  , Member (Env address) effects
diff --git a/src/Data/Abstract/Evaluatable.hs b/src/Data/Abstract/Evaluatable.hs
index ebd8f6d1d..d6eb75d36 100644
--- a/src/Data/Abstract/Evaluatable.hs
+++ b/src/Data/Abstract/Evaluatable.hs
@@ -27,7 +27,7 @@ import Control.Abstract.Environment as X hiding (runEnvironmentError, runEnviron
 import Control.Abstract.Evaluator as X hiding (LoopControl(..), Return(..), catchLoopControl, runLoopControl, catchReturn, runReturn)
 import Control.Abstract.Heap as X hiding (runAddressError, runAddressErrorWith)
 import Control.Abstract.Modules as X (Modules, ModuleResult, ResolutionError(..), load, lookupModule, listModulesInDir, require, resolve, throwResolutionError)
-import Control.Abstract.Value as X hiding (Boolean(..), Function(..))
+import Control.Abstract.Value as X hiding (Boolean(..), Function(..), While(..))
 import Control.Abstract.ScopeGraph
 import Data.Abstract.Declarations as X
 import Data.Abstract.Environment as X
@@ -53,6 +53,7 @@ class (Show1 constr, Foldable constr) => Evaluatable constr where
           , FreeVariables term
           , Member (Allocator address) effects
           , Member (Boolean value) effects
+          , Member (While value) effects
           , Member (Deref value) effects
           , Member (ScopeEnv address) effects
           , Member (Env address) effects
@@ -93,6 +94,7 @@ type ModuleEffects address value rest
 
 type ValueEffects address value rest
   =  Function address value
+  ': While value
   ': Boolean value
   ': rest
 
diff --git a/src/Data/Abstract/Value/Abstract.hs b/src/Data/Abstract/Value/Abstract.hs
index d28da7322..544335e7e 100644
--- a/src/Data/Abstract/Value/Abstract.hs
+++ b/src/Data/Abstract/Value/Abstract.hs
@@ -3,6 +3,7 @@ module Data.Abstract.Value.Abstract
 ( Abstract (..)
 , runFunction
 , runBoolean
+, runWhile
 ) where
 
 import Control.Abstract as Abstract
@@ -50,6 +51,23 @@ runBoolean = interpret $ \case
   AsBool  _       -> pure True <|> pure False
   Disjunction a b -> runBoolean (Evaluator (a <|> b))
 
+runWhile ::
+  ( Member (Allocator address) effects
+  , Member (Deref Abstract) effects
+  , Member (Env address) effects
+  , Member (Exc (Return address)) effects
+  , Member Fresh effects
+  , Member (Reader ModuleInfo) effects
+  , Member (Reader Span) effects
+  , Member (Resumable (BaseError (AddressError address Abstract))) effects
+  , Member (State (Heap address Abstract)) effects
+  , Ord address
+  , PureEffects effects
+  )
+  => Evaluator address Abstract (While Abstract ': effects) a
+  -> Evaluator address Abstract effects a
+runWhile = undefined
+
 
 instance Ord address => ValueRoots address Abstract where
   valueRoots = mempty
diff --git a/src/Data/Abstract/Value/Concrete.hs b/src/Data/Abstract/Value/Concrete.hs
index a88cf300f..c9d86be10 100644
--- a/src/Data/Abstract/Value/Concrete.hs
+++ b/src/Data/Abstract/Value/Concrete.hs
@@ -1,18 +1,20 @@
-{-# LANGUAGE GADTs, RankNTypes, TypeOperators, UndecidableInstances, LambdaCase #-}
+{-# LANGUAGE GADTs, RankNTypes, TypeOperators, ScopedTypeVariables, UndecidableInstances, LambdaCase #-}
 module Data.Abstract.Value.Concrete
   ( Value (..)
   , ValueError (..)
   , ClosureBody (..)
   , runFunction
   , runBoolean
+  , runWhile
   , materializeEnvironment
   , runValueError
   , runValueErrorWith
   ) where
 
 import qualified Control.Abstract as Abstract
-import Control.Abstract hiding (Boolean(..), Function(..))
+import Control.Abstract hiding (Boolean(..), Function(..), While(..))
 import Data.Abstract.BaseError
+import Data.Abstract.Evaluatable (UnspecializedError)
 import Data.Abstract.Environment (Environment, Bindings, EvalContext(..))
 import qualified Data.Abstract.Environment as Env
 import Data.Abstract.Name
@@ -24,7 +26,7 @@ import Data.Scientific (Scientific, coefficient, normalize)
 import Data.Scientific.Exts
 import qualified Data.Set as Set
 import Data.Word
-import Prologue
+import Prologue hiding (catchError)
 
 data Value address body
   = Closure PackageInfo ModuleInfo (Maybe Name) [Name] (ClosureBody address body) (Environment address)
@@ -116,6 +118,39 @@ runBoolean = interpret $ \case
     if a'' then pure a' else runBoolean (Evaluator b)
 
 
+runWhile :: forall effects address body a .
+  ( PureEffects effects
+  , Member (Deref (Value address body)) effects
+  , Member (Abstract.Boolean (Value address body)) effects
+  , Member (Exc (LoopControl address)) effects
+  , Member (Reader ModuleInfo) effects
+  , Member (Reader Span) effects
+  , Member (Resumable (BaseError (AddressError address (Value address body)))) effects
+  , Member (Resumable (BaseError (ValueError address body))) effects
+  , Member (Resumable (BaseError (UnspecializedError (Value address body)))) effects
+  , Member (State (Heap address (Value address body))) effects
+  , Ord address
+  , Show address
+  )
+  => Evaluator address (Value address body) (Abstract.While (Value address body) ': effects) a
+  -> Evaluator address (Value address body) effects a
+runWhile = interpret $ \case
+  Abstract.While cond body -> loop $ \continue -> do
+    cond' <- runWhile (raiseEff cond)
+    -- let body' = interpose @(Resumable (BaseError (UnspecializedError (Value address body)))) (\(Resumable _) -> pure hole) $
+    --       runWhile (raiseEff body) *> continue
+    let body' = (runWhile (raiseEff body) *> continue) `catchError` (\_ -> pure unit)
+    -- let body' = runWhile (raiseEff body) *> continue
+    ifthenelse cond' body' (pure unit)
+  where
+    loop x = catchLoopControl (fix x) (\ control -> case control of
+      Break value -> deref value
+      -- FIXME: Figure out how to deal with this. Ruby treats this as the result
+      -- of the current block iteration, while PHP specifies a breakout level
+      -- and TypeScript appears to take a label.
+      Continue _  -> loop x)
+
+
 instance AbstractHole (Value address body) where
   hole = Hole
 
diff --git a/src/Data/Abstract/Value/Type.hs b/src/Data/Abstract/Value/Type.hs
index c7c519fb5..cb8eb7ba1 100644
--- a/src/Data/Abstract/Value/Type.hs
+++ b/src/Data/Abstract/Value/Type.hs
@@ -8,10 +8,11 @@ module Data.Abstract.Value.Type
   , unify
   , runFunction
   , runBoolean
+  , runWhile
   ) where
 
 import qualified Control.Abstract as Abstract
-import Control.Abstract hiding (Boolean(..), Function(..), raiseHandler)
+import Control.Abstract hiding (Boolean(..), Function(..), While(..), raiseHandler)
 import Control.Monad.Effect.Internal (raiseHandler)
 import Data.Abstract.Environment as Env
 import Data.Abstract.BaseError
@@ -277,6 +278,25 @@ runBoolean = interpret $ \case
   Abstract.Disjunction t1 t2 -> (runBoolean (Evaluator t1) >>= unify Bool) <|> (runBoolean (Evaluator t2) >>= unify Bool)
 
 
+runWhile ::
+  ( Member (Allocator address) effects
+  , Member (Deref Type) effects
+  , Member (Env address) effects
+  , Member (Exc (Return address)) effects
+  , Member Fresh effects
+  , Member (Reader ModuleInfo) effects
+  , Member (Reader Span) effects
+  , Member (Resumable (BaseError TypeError)) effects
+  , Member (Resumable (BaseError (AddressError address Type))) effects
+  , Member (State (Heap address Type)) effects
+  , Member (State TypeMap) effects
+  , Ord address
+  , PureEffects effects
+  )
+  => Evaluator address Type (Abstract.While Type ': effects) a
+  -> Evaluator address Type effects a
+runWhile = undefined
+
 instance AbstractHole Type where
   hole = Hole
 
diff --git a/src/Semantic/Graph.hs b/src/Semantic/Graph.hs
index 575220496..e59c46433 100644
--- a/src/Semantic/Graph.hs
+++ b/src/Semantic/Graph.hs
@@ -42,7 +42,7 @@ import qualified Data.Abstract.ModuleTable as ModuleTable
 import           Data.Abstract.Package as Package
 import           Data.Abstract.Value.Abstract as Abstract
 import           Data.Abstract.Value.Concrete as Concrete
-    (Value, ValueError (..), runBoolean, runFunction, runValueErrorWith)
+    (Value, ValueError (..), runWhile, runBoolean, runFunction, runValueErrorWith)
 import           Data.Abstract.Value.Type as Type
 import           Data.Blob
 import           Data.Coerce
@@ -130,7 +130,7 @@ runCallGraph lang includePackages modules package = do
       runAddressEffects
         = Hole.runAllocator (Located.handleAllocator Monovariant.handleAllocator)
         . Hole.runDeref (Located.handleDeref Monovariant.handleDeref)
-  extractGraph <$> runEvaluator (runGraphAnalysis (evaluate lang analyzeModule analyzeTerm runAddressEffects (Abstract.runBoolean . Abstract.runFunction) modules))
+  extractGraph <$> runEvaluator (runGraphAnalysis (evaluate lang analyzeModule analyzeTerm runAddressEffects (Abstract.runBoolean . Abstract.runWhile . Abstract.runFunction) modules))
 
 runImportGraphToModuleInfos :: ( Declarations term
                                , Evaluatable (Base term)
@@ -198,7 +198,7 @@ runImportGraph lang (package :: Package term) f =
       runAddressEffects
         = Hole.runAllocator Precise.handleAllocator
         . Hole.runDeref Precise.handleDeref
-  in extractGraph <$> runEvaluator (runImportGraphAnalysis (evaluate lang analyzeModule id runAddressEffects (Concrete.runBoolean . Concrete.runFunction coerce coerce) (ModuleTable.toPairs (packageModules package) >>= toList . snd)))
+  in extractGraph <$> runEvaluator (runImportGraphAnalysis (evaluate lang analyzeModule id runAddressEffects (Concrete.runBoolean . Concrete.runWhile . Concrete.runFunction coerce coerce) (ModuleTable.toPairs (packageModules package) >>= toList . snd)))
 
 type ConcreteEffects address rest
   =  Reader Span
@@ -285,7 +285,7 @@ parsePythonPackage parser project = do
   strat <- case find ((== (projectRootDir project </> "setup.py")) . filePath) (projectFiles project) of
     Just setupFile -> do
       setupModule <- fmap snd <$> parseModule project parser setupFile
-      fst <$> runAnalysis (evaluate (Proxy @'Language.Python) id id runAddressEffects (Concrete.runBoolean . Concrete.runFunction coerce coerce . runPythonPackaging) [ setupModule ])
+      fst <$> runAnalysis (evaluate (Proxy @'Language.Python) id id runAddressEffects (Concrete.runBoolean . Concrete.runWhile . Concrete.runFunction coerce coerce . runPythonPackaging) [ setupModule ])
     Nothing -> pure PythonPackage.Unknown
   case strat of
     PythonPackage.Unknown -> do
diff --git a/src/Semantic/REPL.hs b/src/Semantic/REPL.hs
index c527a6d90..3ae64969f 100644
--- a/src/Semantic/REPL.hs
+++ b/src/Semantic/REPL.hs
@@ -106,7 +106,7 @@ repl proxy parser paths = defaultConfig debugOptions >>= \ config -> runM . runD
     . runReader (packageInfo package)
     . runState (lowerBound @Span)
     . runReader (lowerBound @Span)
-    $ evaluate proxy id (withTermSpans . step (fmap (\ (x:|_) -> moduleBody x) <$> ModuleTable.toPairs (packageModules (fst <$> package)))) (Precise.runAllocator . Precise.runDeref) (Concrete.runBoolean . Concrete.runFunction coerce coerce) modules
+    $ evaluate proxy id (withTermSpans . step (fmap (\ (x:|_) -> moduleBody x) <$> ModuleTable.toPairs (packageModules (fst <$> package)))) (Precise.runAllocator . Precise.runDeref) (Concrete.runBoolean . Concrete.runWhile . Concrete.runFunction coerce coerce) modules
 
 -- TODO: REPL for typechecking/abstract semantics
 -- TODO: drive the flow from within the REPL instead of from without
diff --git a/src/Semantic/Util.hs b/src/Semantic/Util.hs
index 3e4d99181..857827572 100644
--- a/src/Semantic/Util.hs
+++ b/src/Semantic/Util.hs
@@ -108,7 +108,7 @@ evaluateProject' (TaskConfig config logger statter) proxy parser paths = either
        (runReader (packageInfo package)
        (runState (lowerBound @Span)
        (runReader (lowerBound @Span)
-       (evaluate proxy id withTermSpans (Precise.runAllocator . Precise.runDeref) (Concrete.runBoolean . Concrete.runFunction coerce coerce) modules)))))))
+       (evaluate proxy id withTermSpans (Precise.runAllocator . Precise.runDeref) (Concrete.runBoolean . Concrete.runWhile . Concrete.runFunction coerce coerce) modules)))))))
 
 evaluatePythonProjects proxy parser lang path = runTaskWithOptions debugOptions $ do
   project <- readProject Nothing path lang []
@@ -121,7 +121,7 @@ evaluatePythonProjects proxy parser lang path = runTaskWithOptions debugOptions
        (runReader (packageInfo package)
        (runState (lowerBound @Span)
        (runReader (lowerBound @Span)
-       (evaluate proxy id withTermSpans (Precise.runAllocator . Precise.runDeref) (Concrete.runBoolean . Concrete.runFunction coerce coerce) modules)))))))
+       (evaluate proxy id withTermSpans (Precise.runAllocator . Precise.runDeref) (Concrete.runBoolean . Concrete.runWhile . Concrete.runFunction coerce coerce) modules)))))))
 
 
 evaluateProjectWithCaching proxy parser path = runTaskWithOptions debugOptions $ do
@@ -133,7 +133,7 @@ evaluateProjectWithCaching proxy parser path = runTaskWithOptions debugOptions $
        (runReader (lowerBound @Span)
        (runReader (lowerBound @(ModuleTable (NonEmpty (Module (ModuleResult Monovariant)))))
        (raiseHandler (runModules (ModuleTable.modulePaths (packageModules package)))
-       (evaluate proxy id withTermSpans (Monovariant.runAllocator . Monovariant.runDeref) (Type.runBoolean . Type.runFunction) modules))))))
+       (evaluate proxy id withTermSpans (Monovariant.runAllocator . Monovariant.runDeref) (Type.runBoolean . Type.runWhile . Type.runFunction) modules))))))
 
 
 parseFile :: Parser term -> FilePath -> IO term