Usually around 18 months, but I had a little boy that took two naps until he was almoat 2 1/2. After 18 months it was usually just a 45min morning nap, then 2hr in the afternoon. Never effected his sleep at night. But mom was BIG on naps. She still had him lay down for an hour or so every day trhough Kindergarten (and a little in first grade) just to give him some "calm" time. Made a huge difference. He was probably my only kid at the time that actually slept a good amount at night
