I've recently discovered that it is bad form to have #includes in your header files because anyone who uses your code gets all those extra includes they won't necessarily want. However, for classes that have member variables defined as a type of another class, what's the alternative? For example, I was doing things the following way for the longest time: /* Header file for class myGrades */ #include <vector> //bad #include "classResult.h" //bad class myGrades { vector<classResult> grades; int average; int bestScore; } (Please excuse the fact that this is a highly artificial example) So, if I want to get rid of the #include lines, is there any way I can keep the vector or do I have to approach programming my code in an entirely different way?