Dear Boost::python experts, I am trying to use a custom shared pointer type instead of boost::shared_pointer, in my case Teuchos::RCP from the Trilinos project. The details of Teuchos::RCP should not matter much here. In any case there is a Doxygen documentation on the Trilinos webpage. For completeness I attached a simple example code, but let me explain here the problem. I have two simple classes A and B, where B is derived from A. The C++-functions: void computeOnA(Teuchos::RCP<A> a) { a->a *= 2; } and void computeOnAs(boost::shared_ptr<A> a) { a->a *= 2; } both work nicely from python. The function void computeOnTupleOfAs(const tuple& as) { for(int i = 0; i < len(as); ++i) { boost::shared_ptr<A> a = extract<boost::shared_ptr<A> >(as[i]); computeOnAs(a); } } also works nicely, given both tuples containing instances of A or the derived class B as expected. However the function: void computeOnTupleOfA(const tuple& as) { for(int i = 0; i < len(as); ++i) { Teuchos::RCP<A> a = extract<Teuchos::RCP<A> >(as[i]); computeOnA(a); } } only works given tuples of A and not the derived class B, the following error is shown: TypeError: No registered converter was able to produce a C++ rvalue of type Teuchos::RCP<A> from this Python object of type B. So my question is, which magic do I need to do (I am willing to use certain internals of boost::python) so that B elements can be extracted from tuples of Bs. I currently only provide the functions: T* get_pointer(Teuchos::RCP<T> const& p) T* get_pointer(Teuchos::RCP<T>& p) Thanks for any help, Holger