Abstract: A shower door jamb assembly is comprised of a separate latch jamb member having a perpendicularly extending leg portion and jamb support wherein the jamb support includes a jamb support base, which adjustably holds the jamb member, and a mounting frame structure. The jamb support base has a transversely oriented receiving slot extending laterally through the base to releasably hold and constrain the movement of the extending leg portion of the latch jamb member. Adjustment screws releasably secure the latch jamb member within the jamb support base receiving slot whereby the latch jamb member, by a transverse plane adjustment, can be made to conform to the plane of the shower door before the latch jamb is secured into a fixed, completely installed position.