diff --git a/README.md b/README.md
index 621306d..e65dd40 100644
--- a/README.md
+++ b/README.md
@@ -156,7 +156,7 @@ if __name__ == '__main__':
 
     while result == NodeStatus.ACTIVE:
         result = count.tick()
-        print result
+        print(result)
         time.sleep(0.1)
 ```
 
@@ -172,7 +172,7 @@ if __name__ == '__main__':
 
     for i in range(0, 10):
         result = repeat.tick()
-        print result
+        print(result)
         time.sleep(0.1)
 ```
 
@@ -203,7 +203,7 @@ if __name__ == '__main__':
 
     while result == NodeStatus.ACTIVE:
         result = finish_counts.tick()
-        print result
+        print(result)
         time.sleep(0.1)
 ```
 Here is also an example of how to use the blackboard to set node parameters.
diff --git a/example/example.py b/example/example.py
index 92c38f2..b6fc563 100755
--- a/example/example.py
+++ b/example/example.py
@@ -14,6 +14,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from __future__ import absolute_import
+from __future__ import print_function
 import time
 
 from task_behavior_engine.branch import Sequencer
@@ -21,6 +23,7 @@
 from task_behavior_engine.tree import Blackboard
 from task_behavior_engine.tree import Node
 from task_behavior_engine.tree import NodeStatus
+from six.moves import range
 
 
 class Count(Node):
@@ -78,17 +81,17 @@ def cleanup(self, nodedata):
 
 if __name__ == '__main__':
 
-    print "Running example 1 -- using a node"
+    print("Running example 1 -- using a node")
 
     count = Count(name="count_index")
     result = NodeStatus(NodeStatus.ACTIVE)
 
     while result == NodeStatus.ACTIVE:
         result = count.tick()
-        print result
+        print(result)
         time.sleep(0.1)
 
-    print "Running example 2 (10 times) -- using a decorator"
+    print("Running example 2 (10 times) -- using a decorator")
 
     count = Count(name="count_index")
     repeat = Repeat(name="repeat_count", child=count)
@@ -96,10 +99,10 @@ def cleanup(self, nodedata):
 
     for i in range(0, 10):
         result = repeat.tick()
-        print result
+        print(result)
         time.sleep(0.1)
 
-    print "Running example 3 -- using a behavior"
+    print("Running example 3 -- using a behavior")
 
     b = Blackboard()
 
@@ -121,5 +124,5 @@ def cleanup(self, nodedata):
 
     while result == NodeStatus.ACTIVE:
         result = finish_counts.tick()
-        print result
+        print(result)
         time.sleep(0.1)
diff --git a/setup.py b/setup.py
index 3a105c4..82de965 100644
--- a/setup.py
+++ b/setup.py
@@ -1,11 +1,20 @@
 ## ! DO NOT MANUALLY INVOKE THIS setup.py, USE CATKIN INSTEAD
 
+from __future__ import absolute_import
 from distutils.core import setup
 from catkin_pkg.python_setup import generate_distutils_setup
 
 # fetch values from package.xml
 setup_args = generate_distutils_setup(
     packages=['task_behavior_engine',],
-    package_dir={'': 'src'})
+    package_dir={'': 'src'},
+    classifiers=[
+        'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 3'
+    ],
+    install_requires=[
+        'six'
+    ],
+)
 
 setup(**setup_args)
diff --git a/src/task_behavior_engine/branch.py b/src/task_behavior_engine/branch.py
index 8ed6a83..d03b7b4 100644
--- a/src/task_behavior_engine/branch.py
+++ b/src/task_behavior_engine/branch.py
@@ -13,11 +13,12 @@
 # under the License.
 
 
+from __future__ import absolute_import
 import logging
 import random
 
-from tree import Behavior
-from tree import NodeStatus
+from .tree import Behavior
+from .tree import NodeStatus
 
 logger = logging.getLogger(__name__)
 
diff --git a/src/task_behavior_engine/decorator.py b/src/task_behavior_engine/decorator.py
index 151db93..6d1182f 100644
--- a/src/task_behavior_engine/decorator.py
+++ b/src/task_behavior_engine/decorator.py
@@ -12,10 +12,11 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from __future__ import absolute_import
 import logging
 
-from tree import Decorator
-from tree import NodeStatus
+from .tree import Decorator
+from .tree import NodeStatus
 
 logger = logging.getLogger(__name__)
 
diff --git a/src/task_behavior_engine/node.py b/src/task_behavior_engine/node.py
index 891ea46..0bbb324 100644
--- a/src/task_behavior_engine/node.py
+++ b/src/task_behavior_engine/node.py
@@ -13,6 +13,7 @@
 # under the License.
 
 
+from __future__ import absolute_import
 from task_behavior_engine.tree import Node
 from task_behavior_engine.tree import NodeStatus
 
diff --git a/src/task_behavior_engine/tree.py b/src/task_behavior_engine/tree.py
index 20b4303..29e1550 100644
--- a/src/task_behavior_engine/tree.py
+++ b/src/task_behavior_engine/tree.py
@@ -13,6 +13,7 @@
 # under the License.
 
 
+from __future__ import absolute_import
 import logging
 import threading
 import uuid
@@ -32,13 +33,13 @@ def __init__(self):
         self._locks = {}
 
     def __contains__(self, key):
-        return key in self._data.keys()
+        return key in list(self._data.keys())
 
     def __getattr__(self, name):
         """ Override getattr to be thread safe. """
         if name[0] == '_':
             return object.__getattr__(self, name)
-        if not name in self._locks.keys():
+        if not name in list(self._locks.keys()):
             self._locks[name] = threading.Lock()
 
         with self._locks[name]:
@@ -51,7 +52,7 @@ def __setattr__(self, name, value):
         if name[0] == '_':
             return object.__setattr__(self, name, value)
 
-        if not name in self._locks.keys():
+        if not name in list(self._locks.keys()):
             self._locks[name] = threading.Lock()
 
         self._locks[name].acquire()
@@ -79,7 +80,7 @@ def get_data(self, key, default=None):
             @param default (None) The default value
             @throws KeyError if key not found and default not set
         """
-        if not key in self._data.keys():
+        if not key in list(self._data.keys()):
             self._data[key] = default
         return self._data[key]
 
diff --git a/test/test_branch.py b/test/test_branch.py
index 6143f20..cf0a62b 100644
--- a/test/test_branch.py
+++ b/test/test_branch.py
@@ -12,6 +12,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from __future__ import absolute_import
 from nose.tools import assert_equal
 
 from task_behavior_engine.branch import All
diff --git a/test/test_decorator.py b/test/test_decorator.py
index 82019f5..d5a54bc 100644
--- a/test/test_decorator.py
+++ b/test/test_decorator.py
@@ -13,6 +13,7 @@
 # under the License.
 
 
+from __future__ import absolute_import
 from nose.tools import assert_equal
 
 from task_behavior_engine.decorator import Fail
diff --git a/test/test_tree.py b/test/test_tree.py
index e48e314..285772e 100644
--- a/test/test_tree.py
+++ b/test/test_tree.py
@@ -12,6 +12,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from __future__ import absolute_import
 from nose.tools import assert_equal
 from nose.tools import assert_not_equal
 from nose.tools import assert_raises
@@ -46,10 +47,10 @@ def test_assignment(self):
     def test_keys(self):
         nd = NodeData()
         nd.key1 = "first key"
-        assert_equal(nd.keys(), ['key1'])
+        assert_equal(list(nd.keys()), ['key1'])
         nd.key2 = "second key"
-        assert_equal(True, 'key2' in nd.keys())
-        assert_equal(True, 'key1' in nd.keys())
+        assert_equal(True, 'key2' in list(nd.keys()))
+        assert_equal(True, 'key1' in list(nd.keys()))
 
     def test_get_data(self):
         nd = NodeData()
@@ -138,7 +139,7 @@ def test_node_memory(self):
         assert_equal(b._get_node_memory("uuid"), {})
         # test unknown uuid memory
         memory = b._get_node_memory("test_uuid")
-        assert_equal(memory.keys(), ['node_data', 'remapping'])
+        assert_equal(list(memory.keys()), ['node_data', 'remapping'])
         # test _get_node_memory
         memory['test_memory'] = 'test'
         memory = b._get_node_memory("test_uuid")
@@ -149,7 +150,7 @@ def test_memory(self):
         # test manually set memory
         node_memory = {'node_data': {'test_memory': 'test'}, 'remapping': {}}
         node_data = b._get_node_data(node_memory)
-        assert_equal(node_data.keys(), ['test_memory'])
+        assert_equal(list(node_data.keys()), ['test_memory'])
         # test non-existing memory
         assert_raises(KeyError, b.get, 'test', 'node_scope')
         # test save