A infant positioning kit assembly for positioning an infant in a supine position while in a crib includes a mattress cover that has a top wall, a bottom wall and a perimeter wall that is attached to and extends between the top and bottom walls. The bottom wall has a mattress aperture extending therethrough for inserting a mattress into the mattress cover. An elastic band is attached to and is coextensive with a perimeter edge of the aperture and a first mating member is attached to the top wall. An attachment member is configured to be worn by an infant and a second mating member is attached to the attachment member. The second mating member is releasably attachable to the first mating member to retain an infant in a selected position on the mattress cover. The first and second mating members comprise hook and loop couplers.