I've had students age 4 and 5 that have been ready, and 8 year olds that are not. Just depends on the child. There seems to be a big push to start piano lessons at a young age - which is fine with me. However, if I had my choice, I would wait until 7. This is a great age: reading is secure, they have a bit more independence, but they are still young enough to enjoy the kiddie-music. I personally do not see any disadvantages to waiting, but I do see a possible disadvantage to starting too early. I think Kindermusik-style programs can fill in the gap nicely.