Based off fascinating children stories (the railway series) Thomas and friends has had gone off to a good start until 2004 when the show first began to experience bad writing. I would recommend that seasons 8-12 would be best for 2 year olds to watch while some of the more classic season be watching for 5+ year olds. There should be no restrictions for a child to stop watching the show, as Thomas and friends can please old and new fans of the show. Would not recommend watch the new series Thomas and friends: big world, big adventures. But rather stuck to a more simpler time in the franchise.