1) When is it appropriate to use adjacency_list directly vs using directed_graph and undirected_graph? 2) I am trying to iterate over the edges of a directed_graph: http://codepad.org/jO3rJLtF In the first method I tried: typedef boost::graph_traits < Graph >::out_edge_iterator out_edge_iterator; std::pair<out_edge_iterator, out_edge_iterator> outEdges = boost::out_edges(v1, g); , memory addresses seem to be output instead of vertex ids. In the second method: typedef boost::property_map<Graph, boost::vertex_index_t>::type IndexMap; IndexMap index = get(boost::vertex_index, g); , vertex ids are output, but I didn't specify if I wanted in edges or out edges? When using adjacency_list directly, I used to have to specify boost::bidirectionalS: typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS> Graph; Is something like that required when using directed_graph? Thanks, David