diff --git a/src/HushGP/GP.hs b/src/HushGP/GP.hs
index 5879ee0..7cdd5d8 100644
--- a/src/HushGP/GP.hs
+++ b/src/HushGP/GP.hs
@@ -9,6 +9,7 @@ import HushGP.Genome
 import HushGP.State
 import HushGP.GP.Variation
 import HushGP.GP.Downsample
+import HushGP.Utility
 
 -- import Debug.Trace (trace, traceStack)
 
@@ -21,7 +22,7 @@ generatePopulation pushArgs = do
 
 -- | Evaluates a population of plushies with the error function passed in via PushArgs and sorts them.
 -- TODO: Need to make this runnable in parallel too.
-evaluatePopulation :: PushArgs -> ([[Gene]], [Gene]) -> [Individual] -> [Individual]
+evaluatePopulation :: PushArgs -> ([[Gene]], [Gene], [Int]) -> [Individual] -> [Individual]
 evaluatePopulation pushArgs passedTrainingData population = sort $ zipWith updateIndividual (map (errorFunction pushArgs pushArgs passedTrainingData . plushy) population) population
 
 -- | A helper function used in evaluatePopulation. Takes a [Double] as the error scores and an individual.
@@ -29,19 +30,21 @@ evaluatePopulation pushArgs passedTrainingData population = sort $ zipWith updat
 updateIndividual :: [Double] -> Individual -> Individual
 updateIndividual errors ind = ind {totalFitness = Just (sum errors), fitnessCases = Just errors}
 
--- | The start of the gp loop. TODO: Make this more accurate later.
+-- | The start of the gp loop. Generates the population and then calls
+-- gpLoop' with modifications to the variables if needed.
 gpLoop :: PushArgs -> IO ()
 gpLoop pushArgs = do
   unEvaledPopulation <- generatePopulation pushArgs
-  -- let evaledPop = evaluatePopulation pushArgs unEvaledPopulation
-  -- print evaledPop
-  print "placeholder for now"
+  let indexedTrainingData = makeIndexedTrainingData (trainingData pushArgs)
+  gpLoop' pushArgs 0 0 unEvaledPopulation indexedTrainingData
+  -- print "do this later"
+
 
 -- | The guts of the GP loop. Where the work gets done after the initialization happens
 -- in the main gpLoop function. The first Int holds the generation count. The second Int
 -- holds the evaluation count. The list of Individuals is the population. The last parameter is
 -- the training data (possibly downsampled).
-gpLoop' :: PushArgs -> Int -> Int -> [Individual] -> ([[Gene]], [Gene]) -> IO ()
+gpLoop' :: PushArgs -> Int -> Int -> [Individual] -> ([[Gene]], [Gene], [Int]) -> IO ()
 gpLoop' pushArgs generation evaluations population indexedTrainingData = do
   print "Put information about each generation here."
   when bestIndPassesDownsample $ print $ "Semi Success Generation: " <> show generation
@@ -56,17 +59,18 @@ gpLoop' pushArgs generation evaluations population indexedTrainingData = do
               print "Total test error simplified: " <> undefined -- Implement later
               print $ "Simplified plushy: " <> undefined -- show simplifiedPlushy
               print $ "Simplified program: " <> undefined -- show plushyToPush simplifiedPlushy
-        | (not (enableDownsampling epsilonPushArgs) && (generation >= maxGenerations epsilonPushArgs)) || (enableDownsampling epsilonPushArgs && (evaluations >= (maxGenerations epsilonPushArgs * length population * length (fst indexedTrainingData)))) =
-          print "Incomplete Run, saving the best so far."
+        | (not (enableDownsampling epsilonPushArgs) && (generation >= maxGenerations epsilonPushArgs)) || (enableDownsampling epsilonPushArgs && (evaluations >= (maxGenerations epsilonPushArgs * length population * length (tfst indexedTrainingData)))) =
+          print $ "Best individual: " <> show (plushy bestInd)
         | otherwise = gpLoop' pushArgs (succ generation)
-            (evaluations + (populationSize pushArgs * length (fst $ trainingData pushArgs)) + (if generation `mod` downsampleParentsGens pushArgs == 0 then length parentReps * (length (fst indexedTrainingData) - length (fst $ trainingData pushArgs)) else 0) + (if bestIndPassesDownsample then length (fst indexedTrainingData) - length (fst $ trainingData pushArgs) else 0))
-            (if elitism pushArgs then bestInd : replicate (populationSize epsilonPushArgs - 1) (newIndividual epsilonPushArgs evaledPop) else replicate (populationSize epsilonPushArgs) (newIndividual epsilonPushArgs evaledPop))
-            (if enableDownsampling pushArgs && ((generation `mod` downsampleParentsGens pushArgs) == 0) then updateCaseDistances repEvaluatedPop indexedTrainingData indexedTrainingData (informedDownsamplingType pushArgs) (solutionErrorThreshold pushArgs / fromIntegral @Int @Double (length $ fst indexedTrainingData)) else indexedTrainingData)
+            (evaluations + (populationSize pushArgs * length (fst $ trainingData pushArgs)) + (if generation `mod` downsampleParentsGens pushArgs == 0 then length parentReps * (length (tfst indexedTrainingData) - length (fst $ trainingData pushArgs)) else 0) + (if bestIndPassesDownsample then length (tfst indexedTrainingData) - length (fst $ trainingData pushArgs) else 0))
+            (if elitism pushArgs
+              then bestInd : replicate (populationSize epsilonPushArgs - 1) (newIndividual epsilonPushArgs evaledPop)
+              else replicate (populationSize epsilonPushArgs) (newIndividual epsilonPushArgs evaledPop))
+            (if enableDownsampling pushArgs && ((generation `mod` downsampleParentsGens pushArgs) == 0)
+              then updateCaseDistances repEvaluatedPop indexedTrainingData indexedTrainingData (informedDownsamplingType pushArgs) (solutionErrorThreshold pushArgs / fromIntegral @Int @Double (length $ tfst indexedTrainingData))
+              else indexedTrainingData)
   nextAction
   where
-    -- \| This will have downsampling added to it later.
-    loopTrainData :: ([[Gene]], [Gene])
-    loopTrainData = indexedTrainingData
     -- \| This will have downsampling functionality added later.
     parentReps :: [Individual]
     parentReps = []
diff --git a/src/HushGP/GP/Downsample.hs b/src/HushGP/GP/Downsample.hs
index 06dc43e..65960ed 100644
--- a/src/HushGP/GP/Downsample.hs
+++ b/src/HushGP/GP/Downsample.hs
@@ -3,5 +3,7 @@ module HushGP.GP.Downsample where
 import HushGP.State
 import HushGP.Genome
 
-updateCaseDistances :: [Individual] -> ([[Gene]], [Gene]) -> ([[Gene]], [Gene]) -> String -> Double -> ([[Gene]], [Gene])
+updateCaseDistances :: [Individual] -> ([[Gene]], [Gene], [Int]) -> ([[Gene]], [Gene], [Int]) -> String -> Double -> ([[Gene]], [Gene], [Int])
 updateCaseDistances evaledPop downsampleData trainingData informedDownsamplingType solutionThreshold = undefined
+
+-- assignIndiciesToData :: 
diff --git a/src/HushGP/GP/PushArgs.hs b/src/HushGP/GP/PushArgs.hs
index 9f0eddb..d108041 100644
--- a/src/HushGP/GP/PushArgs.hs
+++ b/src/HushGP/GP/PushArgs.hs
@@ -49,7 +49,7 @@ data PushArgs = PushArgs
     -- Arg 2: ([[Gene]], [Gene]) is the input data. Input is the first index and output is the second index.
     -- Arg 3: [Gene] is the plushy representation of a program.
     -- Returns the error list for a given set of inputs of type [Double].
-    errorFunction :: PushArgs -> ([[Gene]], [Gene]) -> [Gene] -> [Double],
+    errorFunction :: PushArgs -> ([[Gene]], [Gene], [Int]) -> [Gene] -> [Double],
     -- | Type of informed downsampling. "solved", "elite", "soft".
     informedDownsamplingType :: String,
     -- | List of instructions to use in the evolutionary run.
diff --git a/src/HushGP/Problems/IntegerRegression.hs b/src/HushGP/Problems/IntegerRegression.hs
index 7abe7c2..2e88c13 100644
--- a/src/HushGP/Problems/IntegerRegression.hs
+++ b/src/HushGP/Problems/IntegerRegression.hs
@@ -57,8 +57,8 @@ loadState plushy vals =
   (loadProgram (plushyToPush plushy) emptyState){_input = Map.fromList (zip [0..] vals)}
 
 -- | The error function for a single set of inputs and outputs.
-intErrorFunction :: PushArgs -> ([[Gene]], [Gene]) -> [Gene] -> [Double]
-intErrorFunction _args (inputData, outputData) plushy =
+intErrorFunction :: PushArgs -> ([[Gene]], [Gene], [Int]) -> [Gene] -> [Double]
+intErrorFunction _args (inputData, outputData, _) plushy =
   map abs $ zipWith (-) (map ((fromIntegral @Integer @Double . (errorHead . _int) . interpretExec) . loadState plushy)  inputData) (map (fromIntegral @Integer @Double . extractGeneInt) outputData)
 
 intPushArgs :: PushArgs
@@ -76,7 +76,8 @@ intPushArgs = defaultPushArgs
     tournamentSize = 5,
     umadRate = 0.1,
     variation = Map.fromList [("umad", 1.0), ("crossover", 0.0)],
-    elitism = False
+    elitism = False,
+    enableDownsampling = False
   }
 
 main :: IO ()
diff --git a/src/HushGP/Utility.hs b/src/HushGP/Utility.hs
index 384710c..3157f45 100644
--- a/src/HushGP/Utility.hs
+++ b/src/HushGP/Utility.hs
@@ -13,3 +13,24 @@ randomInstruction instructions = do
 -- | Generates a list of random instructions from a list of instructions passed in.
 randomInstructions :: Int -> [Gene] -> IO [Gene]
 randomInstructions amt instructions = replicateM amt (randomInstruction instructions)
+
+-- |Utility function: Used for indexed training data. Takes the first element of triple.
+tfst :: (a, b, c) -> a
+tfst (x, _, _) = x
+
+-- |Utility function: Used for indexed training data. Takes the second element of triple.
+tsnd :: (a, b, c) -> b
+tsnd (_, x, _) = x
+
+-- |Utility function: Used for indexed training data. Takes the third element of triple.
+-- The third element in the context of indexed training data represents the index assigned.
+thrd :: (a, b, c) -> c
+thrd (_, _, x) = x
+
+-- |Utility function: Converts a tuple to a triple with a passed value.
+tupleToTriple :: (a, b) -> c -> (a, b, c)
+tupleToTriple (x, y) z = (x, y, z)
+
+-- |Utility function: Converts the training data passed in to an indexed representation
+makeIndexedTrainingData :: ([[Gene]], [Gene]) -> ([[Gene]], [Gene], [Int])
+makeIndexedTrainingData (inputs, outputs) = (inputs, outputs, [0..(length inputs)])