The reproductive ecology of the inland silverside, Menidia beryllina, was studied during February 1988-March 1989 at Robinson Point, Blackwater Bay, Florida. Environmental variables including pH, rainfall, salinity, water temperature and dissolved oxygen were measured weekly or biweekly. Fish were sampled weekly with a seine designed to catch adult, juvenile and young-of-the-year (YOY) individuals. Most reproductive activity occurred during February-April 1988. The maximum mean weekly female gonadosomatic index (GSI) of 12.5 occurred in April. Fecundity ranged from 63 to 419 hydrated eggs per female. The maximum mean weekly male GSI of 6.1 occurred in early March. Catches of YOY individuals 7.6-37.5 mm SL was greatest in May. These YOY individuals matured in July-September and spawned. The reproductive activity resulted in recruitment of a second group of YOY fish into the population during August-October. Growth rates of YOY in May-July, calculated by regression methods from weekly frequency distributions of standard length, was 0.34 mm/day for females and 0.31 mm/day for males. (Copyright (c) 1992 by the American Society of Ichthyologists and Herpetologists.)