Hi, using either the latest git repo or 2.2.36 and running: /usr/bin/python3.3 -c 'import graph_tool ; print(graph_tool.__version__)' (or even python3.3 -c 'import graph_tool') results in: Traceback (most recent call last): File "<string>", line 1, in <module> File "/usr/lib64/python3.3/site-packages/graph_tool/__init__.py", line 101, in <module> dl_import("from . import libgraph_tool_core as libcore") File "/usr/lib64/python3.3/site-packages/graph_tool/dl_import.py", line 57, in dl_import exec(import_expr, local_dict, global_dict) File "<string>", line 1, in <module> ImportError: /usr/lib64/python3.3/site-packages/graph_tool/libgraph_tool_core.so: undefined symbol: _ZN5boost6python6detail11init_moduleER11PyModuleDefPFvvE It appears that -lboost_python3_3-mt is not being used, even though my system default is py3.3. the interesting part of the ./configure log shows: graph-tool will be installed at: /usr/lib64/python3.3/site-packages =========================== Using python version: 3.3.5 =========================== checking for boostlib >= 1.53.0... yes checking whether the Boost::Python library is available... yes checking for exit in -lboost_python... no checking for exit in -lboost_python... (cached) no checking for exit in -lboost_python-2.7-mt... yes if I recompile boost without py2.7 support (py3.3 only), then the interesting part of the ./configure log shows: graph-tool will be installed at: /usr/lib64/python3.3/site-packages =========================== Using python version: 3.3.5 =========================== checking for boostlib >= 1.53.0... yes checking whether the Boost::Python library is available... yes checking for exit in -lboost_python... no checking for exit in -lboost_python... (cached) no checking for exit in -lboost_python-2.7... no checking for exit in -lboost_python-3-mt... yes and the test command works: $/usr/bin/python3.3 -c 'import graph_tool ; print(graph_tool.__version__)' 2.2.36 (commit e3865108, Thu Jan 8 17:03:44 2015 +0100) More detail on this issue is available in the gentoo bug tracker: https://bugs.gentoo.org/show_bug.cgi?id=536734 How do we get the Makefile to have BOOST_PYTHON_LIB = boost_python-3-mt instead of BOOST_PYTHON_LIB = boost_python-2.7-mt when boost has been compiled for 2.7 and 3.3? Thanks! -Justin Keogh