Abstract: The invention provides a bottle adapter for securing an attachment to a bottle. The attachment can be a nipple and ring assembly for a baby bottle. The bottle adapter has a base, and the base has a bottom end and a top end. A bottle receiving portion extends from the bottom end of the base, and an attachment receiving portion extends from the top end of the base. The bottle receiving portion includes an outer bottle receiving ring and an inner bottle receiving ring. The attachment receiving portion includes an outer attachment receiving ring and an inner attachment receiving ring. The base of the bottle adapter also includes a passage defined therein for allowing the flow of a fluid from the bottle receiving portion to the attachment receiving portion of the bottle adapter. In an embodiment of the invention, the bottle adapter is sized to adapt both a disposable liner bottle and a traditional bottle to receive both a disposable liner bottle nipple and ring assembly and a traditional nipple and ring assembly.