Thank the Tiny Baby Jesus for the Magic Merlin suit! My daughter slept in a Rock N Play for her first 4-5 months (also a must have!) And this little suit helped to transition her to her crib seemlisly! She was easily busting out of traditional swaddled, but this thing gave her the security she needed! We started off in the small size, bought the large size and ended up only using it for a couple more weeks...but it was totally worth the money. Nearly anything that lrgit helps a baby sleep is WORTH. IT. I wish we would have known about this with our first baby...