A convertible cargo case for a wagon is provided. The cargo case has a housing and a frame. The frame has frame members in a first plane and frame members in a second plane substantially parallel to the first plane. Cross members connect the frame members in the first plane with the frame members in the second plane. The housing has a first side wall, a second side wall, a third side wall, a fourth side wall, and a bottom wall defining a cavity. The housing is releasably secured to the frame with a plurality of locks. The cargo case is positioned adjacent a rear of the wagon in a cargo use configuration, and the wagon is positioned partially within the cavity of the housing in a storage configuration.