The reproductive success of the Snowy Plover (Charadrius alexandrinus) nesting on beaches in central Monterey Bay, California, was monitored before (1984 to 1990) and during (1991 to 1999) predator management. From 1984 to 1990, hatching success of the Snowy Plover declined from 66% to 26% and most nest loss was attributed to Red Fox (Vulpes vulpes) predation. From 1991 to 1999, exclosures were used to protect some nests and after 1993, mammalian nest predators were removed. Predator management increased hatching success and the number of chicks hatched per male, but not fledging success or the number of chicks fledged per male. Predation of chicks by avian predators probably limited fledging success. The number of breeding adults did not increase and incubating adults were subject to greater mortality when nesting in exclosures. Our results indicate that exclosures are useful for increasing hatching success, but we caution that widespread use of exclosures may increase adult mortality rates and contribute to a decline in breeding numbers.