A convertible container holding assembly includes a housing fixedly secured to a structure such as an armrest or instrument panel. A base is movable into and out of the housing between retracted and extended positions. The base includes a support and a stabilizing edge. The support and stabilizing edge define a portion of a cupholding area. A stabilizing arm is pivotally secured to the base and is positionable in an infinite number of positions such that it is capable of positively abutting the container when the container is positively abutting the stabilizing edge, regardless of the diameter of the container. A brake prevents the stabilizing arm from moving to its outermost position once it is forced into engagement with the container. The stabilizing arm may be reset by forcing it to its innermost position or by retracting the base into the housing and moving the base back to its extended position.