At http://www.boost.org/libs/graph/doc/adjacency_list.html, there's a table of how graph operations affect iterators and descriptors. That table states that add_vertex will not invalidate vertex descriptors when the vertex list is a vecS. I recently discovered that this is wrong for Boost 1.33.1. That makes sense because adding an edge could cause the vector to be reallocated and therefore all vertex descriptors to become invalid. I would assume this holds for edge descriptors and iterators as well. Is the documentation wrong or has this changed in 1.34? -Dave