Sand seatrout (Cynoscion arenarius) is of commercial and recreational importance to the Gulf states. Spawning behavior, feeding habits, length-weight relationships and standard length-total length relationships were determined for 498. Sand seatrout distribution, gonadal development and the time young-of-the-year appeared in the estuaries indicated that this species spawns near Gulf-to-bay passes in the Gulf of Mexico between March and August with a spawning peak during spring. Fish and crustaceans dominated the diet of sand seatrout, crustaceans occurred more frequently in fish < 160 mm SL and fish predominated in those > 160 mm SL. The length-weight regressions derived from 267 sand seatrout 125-375 mm SL differed between sexes. The standard length-total length relationship was TL= 0.7 + 1.1 SL.