Abstract: A reusable, longitudinally adjustable, readily removable form support member for supporting a concrete construction form in an array of structural members in a building construction. In one embodiment the form support member comprises a spanning member having laterally translatably support pin members secured in recesses in opposed ends of the spanning member for engaging openings in adjacent structural members. The support pins may be movable in a horizontal plane so as to permit their alignment with the structural openings where necessary. The support pin members include block means attached to the rear portions of the support pins, the block means cooperating with respective activating means to move the spanning member in a vertical plane so that an inside surface of the respective end parts of the spanning member contacts a surface of the block means and effect a friction bond which prevents longitudinal movement of the respective parts.