Hi Ann- I finally just got my daughter to drink milk from her sippy cups, I have bought every brand out there seeing if there is one she likes, well we finally found one (the one with OUT the stoppers), but your son will drink milk out of his cup when he is ready, we would give her milk in her cup everyday, and she would push it away, until a couple of weeks ago, she actually drank it, I was so happy! Give him time, he will do it when he is ready! Sorry if I was rambling... Good luck, let us know how it works out!