That's about the age my oldest stopped taking naps. Then we implemented "quiet time" as part of our daily routine. It took a few weeks to really get his full co-operation, but for an hour everyday, we have quiet time and he lays in bed in a dark room (hallway light is on, usually) with a story on CD or music playing. He's allowed to have books in bed with him, as long as he is relaxing a not talking. This is the only way he doesn't start getting into trouble at night, b/c it refreshes him and helps him "keep it together" until bedtime. Some days, he's so tuckered out from morning fun, he'll actually fall asleep, too. I time it with my 16-month old's naptime and it really helps me get things done in the house.