diff --git a/mlp/data_providers.py b/mlp/data_providers.py
index bbd9632..c49e8f3 100644
--- a/mlp/data_providers.py
+++ b/mlp/data_providers.py
@@ -35,23 +35,54 @@ class DataProvider(object):
         """
         self.inputs = inputs
         self.targets = targets
-        self.batch_size = batch_size
-        assert max_num_batches != 0 and not max_num_batches < -1, (
-            'max_num_batches should be -1 or > 0')
-        self.max_num_batches = max_num_batches
+        if batch_size < 1:
+            raise ValueError('batch_size must be >= 1')
+        self._batch_size = batch_size
+        if max_num_batches == 0 or max_num_batches < -1:
+            raise ValueError('max_num_batches must be -1 or > 0')
+        self._max_num_batches = max_num_batches
+        self._update_num_batches()
+        self.shuffle_order = shuffle_order
+        self._current_order = np.arange(inputs.shape[0])
+        if rng is None:
+            rng = np.random.RandomState(DEFAULT_SEED)
+        self.rng = rng
+        self.new_epoch()
+
+    @property
+    def batch_size(self):
+        """Number of data points to include in each batch."""
+        return self._batch_size
+
+    @batch_size.setter
+    def batch_size(self, value):
+        if value < 1:
+            raise ValueError('batch_size must be >= 1')
+        self._batch_size = value
+        self._update_num_batches()
+
+    @property
+    def max_num_batches(self):
+        """Maximum number of batches to iterate over in an epoch."""
+        return self._max_num_batches
+
+    @max_num_batches.setter
+    def max_num_batches(self, value):
+        if value == 0 or value < -1:
+            raise ValueError('max_num_batches must be -1 or > 0')
+        self._max_num_batches = value
+        self._update_num_batches()
+
+    def _update_num_batches(self):
+        """Updates number of batches to iterate over."""
         # maximum possible number of batches is equal to number of whole times
         # batch_size divides in to the number of data points which can be
         # found using integer division
-        possible_num_batches = self.inputs.shape[0] // batch_size
+        possible_num_batches = self.inputs.shape[0] // self.batch_size
         if self.max_num_batches == -1:
             self.num_batches = possible_num_batches
         else:
             self.num_batches = min(self.max_num_batches, possible_num_batches)
-        self.shuffle_order = shuffle_order
-        if rng is None:
-            rng = np.random.RandomState(DEFAULT_SEED)
-        self.rng = rng
-        self.reset()
 
     def __iter__(self):
         """Implements Python iterator interface.
@@ -63,24 +94,33 @@ class DataProvider(object):
         """
         return self
 
-    def reset(self):
-        """Resets the provider to the initial state to use in a new epoch."""
+    def new_epoch(self):
+        """Starts a new epoch (pass through data), possibly shuffling first."""
         self._curr_batch = 0
         if self.shuffle_order:
             self.shuffle()
 
+    def reset(self):
+        """Resets the provider to the initial state."""
+        inv_perm = np.argsort(self._current_order)
+        self._current_order = self._current_order[inv_perm]
+        self.inputs = self.inputs[inv_perm]
+        self.targets = self.targets[inv_perm]
+        self.new_epoch()
+
     def shuffle(self):
         """Randomly shuffles order of data."""
-        new_order = self.rng.permutation(self.inputs.shape[0])
-        self.inputs = self.inputs[new_order]
-        self.targets = self.targets[new_order]
+        perm = self.rng.permutation(self.inputs.shape[0])
+        self._current_order = self._current_order[perm]
+        self.inputs = self.inputs[perm]
+        self.targets = self.targets[perm]
 
     def next(self):
         """Returns next data batch or raises `StopIteration` if at end."""
         if self._curr_batch + 1 > self.num_batches:
-            # no more batches in current iteration through data set so reset
-            # the dataset for another pass and indicate iteration is at end
-            self.reset()
+            # no more batches in current iteration through data set so start
+            # new epoch ready for another pass and indicate iteration is at end
+            self.new_epoch()
             raise StopIteration()
         # create an index slice corresponding to current batch number
         batch_slice = slice(self._curr_batch * self.batch_size,