[Moderator's note: The only apparent connection this message has to Boost is in the subject line. I am approving it on the assumption that the missing declarations for ParentPtr and DerivedPtr are typedefs using boost::shared_ptr.] Hello everyone... I am attempting to do the following: class Parent { public: int m_value; }; class Derived : public Parent { }; void Fn(ParentPtr& pObj) { pObj = ParentPtr(new Parent()); pObj->m_value = 10; } int main() { ParentPtr pParent; DerivedPtr pDerived; Fn(pDerived); return 0; } If I pass the parent pointer, it compiles and works fine. If I pass the derived pointer I get: error C2664: 'Fn' : cannot convert parameter 1 from 'DerivedPtr' to 'ParentPtr &' Does anyone know how to solve my problem? TIA, Drew