Abstract: A concrete screed rail support apparatus which includes a saddle having a channel with open ends and an open top for accommodating a screed rail, and a pair of arms each connected at its proximal end portion to the saddle. Each arm extends outwardly from the saddle and connects to a leg at the distal end portion. Each leg extends toward the concrete pour surface, and the length of each leg between the pour surface and its connection to the distal end portion of the arms is adjustable. Locking mechanisms are provided to fix the position of the legs once adjusted and to lock the screed rail to the saddle. Pads can be used between the pour surface and the legs for stability and to prevent damage to vapor barriers or waterproofing membranes.