Hi, What you  are missing is a color map. One solution is to use bundled properties: #include <boost/config.hpp> #include <vector> #include <map> #include <iostream>                      // for std::cout #include <algorithm>                     // for std::for_each #include <boost/utility.hpp>             // for boost::tie #include <boost/graph/graph_traits.hpp>  // for boost::graph_traits #include <boost/graph/adjacency_list.hpp> #include <boost/graph/connected_components.hpp> using namespace boost; struct Node {  int index;  //****color property******************************  boost::default_color_type m_algo_color;  //****color property****************************** }; struct Boundary {  double something; }; typedef boost::adjacency_list<    boost::setS, boost::listS, boost::undirectedS,    Node, Boundary, boost::setS> Graph; int main(int argc, char*argv[]) {  Graph g(5);  boost::graph_traits<Graph>::vertex_iterator vi, viend;  std::vector< int > c( num_vertices(g) );  int num;  // manually intialize the vertex index,  // because we have listS as vertex list type  int n = 0;  for (tie(vi, viend) = vertices(g); vi != viend; ++vi, ++n) {      g[*vi].index = n;  }  //****modified call******************************  num = connected_components(g, make_iterator_property_map(c.begin(), get(&Node::index, g)), boost::color_map( get(&Node::m_algo_color, g) ));  //****modified call******************************  return 0; } Detlef