diff --git a/caliban_toolbox/pipeline.py b/caliban_toolbox/pipeline.py
index 380ac01..e910e18 100644
--- a/caliban_toolbox/pipeline.py
+++ b/caliban_toolbox/pipeline.py
@@ -32,11 +32,13 @@
 
 def find_sparse_images(labeled_data, cutoff=100):
     """Gets coordinates of images that have very few cells
+
     Args:
-        labeled_data: predictions used for counting number of cells
+        labeled_data: segmentation labels
         cutoff: minimum number of cells per image
+
     Returns:
-        numpy.array: index used to remove sparse images
+        numpy.array: index of images above the threshold
     """
 
     unique_counts = []
@@ -50,7 +52,8 @@ def find_sparse_images(labeled_data, cutoff=100):
 
 
 def save_stitched_npzs(stitched_channels, stitched_labels, save_dir):
-    """Takes corrected labels and channels and saves to NPZ for caliban round 2 checking
+    """Takes corrected labels and channels and saves them into NPZ format
+
     Args:
         stitched_channels: original channel data
         stitched_labels: stitched labels
@@ -66,6 +69,7 @@ def save_stitched_npzs(stitched_channels, stitched_labels, save_dir):
 
 def process_stitched_data(base_dir):
     """Takes stitched output and creates folder of NPZs for review
+
     Args:
         base_dir: directory to read from
     """
@@ -73,8 +77,51 @@ def process_stitched_data(base_dir):
     stitched_labels = xr.load_dataarray(os.path.join(base_dir, 'output', 'stitched_labels.xr'))
     channel_data = xr.load_dataarray(os.path.join(base_dir, 'channel_data.xr'))
 
-    correction_folder = os.path.join(base_dir, 'ready_to_correct')
-    os.makedirs(correction_folder)
+    stitched_folder = os.path.join(base_dir, 'stitched_npzs')
+    os.makedirs(stitched_folder)
 
     save_stitched_npzs(stitched_channels=channel_data, stitched_labels=stitched_labels,
-                       save_dir=correction_folder)
+                       save_dir=stitched_folder)
+
+
+def concatenate_npz_files(npz_list):
+    """Takes a list of NPZ files and combines the X and y keys of each together
+
+    Args:
+        npz_list: list of NPZ files
+
+    Returns:
+        tuple: concatenated X data and y data
+    """
+
+    X_data = []
+    y_data = []
+    for npz in npz_list:
+        X_data.append(npz['X'])
+        y_data.append(npz['y'])
+    X_data = np.concatenate(X_data, axis=0)
+    y_data = np.concatenate(y_data, axis=0)
+    return X_data, y_data
+
+
+def create_combined_npz(npz_dir, save_name):
+    """Takes folder of corrected NPZs and combines together into single NPZ file
+
+    Args:
+        npz_dir: directory containing NPZ files
+        save_name: name for combined NPZ file
+
+    Raises: ValueError if invalid directory name
+    """
+
+    if not os.path.isdir(npz_dir):
+        raise ValueError("Invalid directory name")
+
+    npz_filenames = os.listdir(npz_dir)
+    npz_filenames = [file for file in npz_filenames if '.npz' in file]
+
+    npz_list = [np.load(os.path.join(npz_dir, npz)) for npz in npz_filenames]
+
+    X_concat, y_concat = concatenate_npz_files(npz_list=npz_list)
+
+    np.savez(os.path.join(npz_dir, save_name), X=X_concat, y=y_concat)
diff --git a/caliban_toolbox/pipeline_test.py b/caliban_toolbox/pipeline_test.py
index bec5089..dd1aeda 100644
--- a/caliban_toolbox/pipeline_test.py
+++ b/caliban_toolbox/pipeline_test.py
@@ -32,6 +32,16 @@
 from caliban_toolbox import pipeline
 
 
+def _make_npz_files(npz_num):
+    npz_list = []
+    for i in range(npz_num):
+        X_data = np.zeros((1, 256, 256, 2))
+        y_data = np.zeros((1, 256, 256, 1))
+        npz_list.append({'X': X_data, 'y': y_data})
+
+    return npz_list
+
+
 def test_find_sparse_images():
     images = np.zeros((10, 30, 30, 1))
     sparse_indices = np.random.choice(range(10), 5, replace=False)
@@ -81,3 +91,28 @@ def test_process_stitched_data():
         channels.to_netcdf(os.path.join(temp_dir, 'channel_data.xr'))
 
         pipeline.process_stitched_data(temp_dir)
+
+
+def test_concatenate_npz_files():
+    npz_num = 5
+    npz_list = _make_npz_files(npz_num=npz_num)
+    X_concat, y_concat = pipeline.concatenate_npz_files(npz_list)
+
+    assert X_concat.shape == (npz_num, 256, 256, 2)
+    assert y_concat.shape == (npz_num, 256, 256, 1)
+
+
+def test_create_combined_npz():
+    npz_list = _make_npz_files(5)
+
+    with tempfile.TemporaryDirectory() as temp_dir:
+        for idx, npz in enumerate(npz_list):
+            np.savez(os.path.join(temp_dir, 'test_npz_{}.npz'.format(idx)),
+                     X=npz['X'], y=npz['y'])
+
+        pipeline.create_combined_npz(npz_dir=temp_dir, save_name='combined.npz')
+
+        combined = np.load(os.path.join(temp_dir, 'combined.npz'))
+
+        assert combined['X'].shape == (5, 256, 256, 2)
+        assert combined['y'].shape == (5, 256, 256, 1)