Abstract: A carrier for sports balls and similar articles that is mutually convertible between a back pack and a shoulder bag without the addition or subtraction of any element. The carrier includes a primary bag comprised of a flexible shell of material with an exterior surface that encloses an open inner volume of sufficient size for retaining a sports ball. Upper central, lower central, first lateral, and second lateral coupling elements are affixed to the exterior surface of the primary bag. An elongated and flexible strap with a first end with a selectively disengagable first attaching mechanism, a second end with a selectively disengagable second attaching mechanism, and a body portion couples to the primary bag at two or more of the coupling elements depending on the form that the carrier is to be used.