Abstract: A combination billiard rack convertible between two game configuration, such as a 15-ball configuration and a 9-ball configuration. The rack includes two side members and a base member that cooperate to form a substantially equilateral triangle defining an interior area in a plane of the rack capable of receiving and racking a plurality of billiard balls. Pivotal arms are provided on each of the side members. Each is pivotal about one fixed end at a location proximate a midpoint of each side member for pivotal movement about the fixed end in the plane of the rack. The pivotal arms are pivotal between a first position in which each pivotal arm is parallel with corresponding side members and a second position located within said interior area in which the pivotal arms are non-parallel with corresponding side members and act with the side members and base member to form an internal area of a size smaller than the first configuration.