My son is 2 and he is swimming in these.  He is between the 12th and 7th percentiles for weight and height (tiny parents), so if your child is on the smaller end keep that in mind.  They DO stay up, but they are baggy and can sag with vigorous play.  They do their job, are soft, and absorbent when they need to be so no complaint there.  Just keep sizing in mind!