The reproductive parameters of 1,194 sandbar sharks Carcharhinus plumbeus (701 females, 493 males) were examined for stock assessment. Size and age at 50% maturity was 151.6 cm FL (12.1 years) for males and 154.9 cm (13.1 years) for females; however, the size and age at which 50% of females were in maternal condition was 162.0 cm FL (15.5 years). Males and females showed distinct seasonal reproduction patterns, with peak mating and parturition occurring from April through July. The majority of near-term pregnant and postpartum females were observed in the Florida Keys, which is an extension of the previously reported nursery grounds for sandbar sharks in the western North Atlantic Ocean. Female fecundity averaged 8.0 pups, and there was a significant increase in fecundity with length and age. The ovarian cycle is at least biennial, although there is evidence that some females have triennial cycles.