diff --git a/problem_builder/__init__.py b/problem_builder/__init__.py
index 28e2a153..e69de29b 100644
--- a/problem_builder/__init__.py
+++ b/problem_builder/__init__.py
@@ -1,11 +0,0 @@
-from .mentoring import MentoringBlock, MentoringWithExplicitStepsBlock
-from .step import MentoringStepBlock, ReviewStepBlock
-from .answer import AnswerBlock, AnswerRecapBlock
-from .choice import ChoiceBlock
-from .dashboard import DashboardBlock
-from .instructor_tool import InstructorToolBlock
-from .mcq import MCQBlock, RatingBlock
-from .mrq import MRQBlock
-from .message import MentoringMessageBlock
-from .table import MentoringTableBlock, MentoringTableColumn
-from .tip import TipBlock
diff --git a/problem_builder/tasks.py b/problem_builder/tasks.py
index 8439d784..72c48531 100644
--- a/problem_builder/tasks.py
+++ b/problem_builder/tasks.py
@@ -12,7 +12,7 @@
 from xmodule.modulestore.exceptions import ItemNotFoundError
 
 from .mcq import MCQBlock, RatingBlock
-from problem_builder import AnswerBlock
+from problem_builder.answer import AnswerBlock
 from .questionnaire import QuestionnaireAbstractBlock
 from .sub_api import sub_api
 
diff --git a/problem_builder/tests/integration/base_test.py b/problem_builder/tests/integration/base_test.py
index 3113644f..8661125a 100644
--- a/problem_builder/tests/integration/base_test.py
+++ b/problem_builder/tests/integration/base_test.py
@@ -25,7 +25,7 @@
 # Studio adds a url_name property to each XBlock but Workbench doesn't.
 # Since we rely on it, we need to mock url_name support so it can be set via XML and
 # accessed like a normal field.
-from problem_builder import MentoringBlock
+from problem_builder.mentoring import MentoringBlock
 MentoringBlock.url_name = String()
 
 loader = ResourceLoader(__name__)
diff --git a/problem_builder/tests/integration/test_mentoring.py b/problem_builder/tests/integration/test_mentoring.py
index ec5dc088..97bc04b3 100644
--- a/problem_builder/tests/integration/test_mentoring.py
+++ b/problem_builder/tests/integration/test_mentoring.py
@@ -70,7 +70,7 @@ def assert_status_icon_color(self, color, question_text):
         ('apros', "#ff0000", "QUESTION")
     )
     def test_lms_theme_applied(self, theme, expected_color, question_text):
-        with mock.patch("problem_builder.MentoringBlock.get_theme") as patched_theme:
+        with mock.patch("problem_builder.mentoring.MentoringBlock.get_theme") as patched_theme:
             patched_theme.return_value = _get_mentoring_theme_settings(theme)
             self.assert_status_icon_color(expected_color, question_text)
 
diff --git a/problem_builder/tests/integration/test_questionnaire.py b/problem_builder/tests/integration/test_questionnaire.py
index aabdba6b..db26531a 100644
--- a/problem_builder/tests/integration/test_questionnaire.py
+++ b/problem_builder/tests/integration/test_questionnaire.py
@@ -23,7 +23,7 @@
 import ddt
 from mock import patch, Mock
 
-from problem_builder import MentoringBlock
+from problem_builder.mentoring import MentoringBlock
 from .base_test import MentoringBaseTest
 
 
diff --git a/problem_builder/tests/unit/test_instructor_tool.py b/problem_builder/tests/unit/test_instructor_tool.py
index a9ea64c0..a39c6d46 100644
--- a/problem_builder/tests/unit/test_instructor_tool.py
+++ b/problem_builder/tests/unit/test_instructor_tool.py
@@ -5,7 +5,7 @@
 import unittest
 from mock import Mock, patch
 from xblock.field_data import DictFieldData
-from problem_builder import InstructorToolBlock
+from problem_builder.instructor_tool import InstructorToolBlock
 
 
 @ddt.ddt
diff --git a/problem_builder/tests/unit/test_mentoring.py b/problem_builder/tests/unit/test_mentoring.py
index 6c41d37b..84d8d167 100644
--- a/problem_builder/tests/unit/test_mentoring.py
+++ b/problem_builder/tests/unit/test_mentoring.py
@@ -2,8 +2,8 @@
 import ddt
 from mock import MagicMock, Mock, patch
 from xblock.field_data import DictFieldData
-from problem_builder import MentoringBlock, MentoringMessageBlock, MCQBlock
-from problem_builder.mentoring import _default_theme_config
+from problem_builder.mcq import MCQBlock
+from problem_builder.mentoring import MentoringBlock, MentoringMessageBlock, _default_theme_config
 
 
 @ddt.ddt
diff --git a/problem_builder/tests/unit/test_migration.py b/problem_builder/tests/unit/test_migration.py
index 412027ae..dc70fd42 100644
--- a/problem_builder/tests/unit/test_migration.py
+++ b/problem_builder/tests/unit/test_migration.py
@@ -1,5 +1,5 @@
 import copy
-from problem_builder import MentoringBlock
+from problem_builder.mentoring import MentoringBlock
 from mock import MagicMock, Mock
 import unittest
 from xblock.field_data import DictFieldData
diff --git a/problem_builder/v1/tests/test_upgrade.py b/problem_builder/v1/tests/test_upgrade.py
index dd3a878a..67f68810 100644
--- a/problem_builder/v1/tests/test_upgrade.py
+++ b/problem_builder/v1/tests/test_upgrade.py
@@ -22,7 +22,7 @@
 """
 import ddt
 from lxml import etree
-from problem_builder import MentoringBlock
+from problem_builder.mentoring import MentoringBlock
 from problem_builder.v1.xml_changes import convert_xml_to_v2
 import os.path
 from StringIO import StringIO
diff --git a/problem_builder/v1/upgrade.py b/problem_builder/v1/upgrade.py
index d1bc33d0..f97cc1c7 100644
--- a/problem_builder/v1/upgrade.py
+++ b/problem_builder/v1/upgrade.py
@@ -32,7 +32,7 @@
 import logging
 from lxml import etree
 from mentoring import MentoringBlock
-from problem_builder import MentoringBlock as NewMentoringBlock
+from problem_builder.mentoring import MentoringBlock as NewMentoringBlock
 from StringIO import StringIO
 import sys
 import warnings
diff --git a/setup.py b/setup.py
index f0d5efd6..1c2ef462 100644
--- a/setup.py
+++ b/setup.py
@@ -40,25 +40,25 @@ def package_data(pkg, root_list):
 # Main ##############################################################
 
 BLOCKS = [
-    'problem-builder = problem_builder:MentoringBlock',
-    'step-builder = problem_builder:MentoringWithExplicitStepsBlock',
-    'sb-step = problem_builder:MentoringStepBlock',
-    'sb-review-step = problem_builder:ReviewStepBlock',
+    'problem-builder = problem_builder.mentoring:MentoringBlock',
+    'step-builder = problem_builder.mentoring:MentoringWithExplicitStepsBlock',
+    'sb-step = problem_builder.step:MentoringStepBlock',
+    'sb-review-step = problem_builder.step:ReviewStepBlock',
 
-    'pb-table = problem_builder:MentoringTableBlock',
-    'pb-column = problem_builder:MentoringTableColumn',
-    'pb-answer = problem_builder:AnswerBlock',
-    'pb-answer-recap = problem_builder:AnswerRecapBlock',
-    'pb-mcq = problem_builder:MCQBlock',
-    'pb-rating = problem_builder:RatingBlock',
-    'pb-mrq = problem_builder:MRQBlock',
-    'pb-message = problem_builder:MentoringMessageBlock',
-    'pb-tip = problem_builder:TipBlock',
-    'pb-choice = problem_builder:ChoiceBlock',
+    'pb-table = problem_builder.table:MentoringTableBlock',
+    'pb-column = problem_builder.table:MentoringTableColumn',
+    'pb-answer = problem_builder.answer:AnswerBlock',
+    'pb-answer-recap = problem_builder.answer:AnswerRecapBlock',
+    'pb-mcq = problem_builder.mcq:MCQBlock',
+    'pb-rating = problem_builder.mcq:RatingBlock',
+    'pb-mrq = problem_builder.mrq:MRQBlock',
+    'pb-message = problem_builder.message:MentoringMessageBlock',
+    'pb-tip = problem_builder.tip:TipBlock',
+    'pb-choice = problem_builder.choice:ChoiceBlock',
 
-    'pb-dashboard = problem_builder:DashboardBlock',
-    'pb-data-export = problem_builder:InstructorToolBlock',  # Deprecated; use pb-instructor-tool instead
-    'pb-instructor-tool = problem_builder:InstructorToolBlock',
+    'pb-dashboard = problem_builder.dashboard:DashboardBlock',
+    'pb-data-export = problem_builder.instructor_tool:InstructorToolBlock',  # Deprecated; use 'pb-instructor-tool' now
+    'pb-instructor-tool = problem_builder.instructor_tool:InstructorToolBlock',
 ]
 
 setup(