A rail fastener assembly includes a rail seat laterally shiftable incrementally to properly position a supported rail. Anchoring of the seat to an underlying foundation is achieved by a clamp ring surrounding the periphery of the seat and including a plurality of fastener-receiving openings having their centers variably spaced from the seat. Rotation of the clamp ring presents at least two fastener-receiving openings in overlying registry with hold-down elements in the foundation to enable the application of fasteners through the clamp ring to secure the seat to the foundation. A pair of symmetrical spring clips engage shoulders on the seat and include a medial hold-down portion biased against the rail flanges and fixed, distal shoulder engaging portions overlying each rail flange but normally spaced thereabove to limit deflection of the clips during vertical movement of the rail.