Brook silverside (Labidesthes sicculus) eggs, larvae, and juveniles were collected with a plankton net from the Peace River, Florida. Eggs had two or three attachment filaments (mode = 2) and a mean diameter of 1.2 mm. Oil globules were present in the yolk, and decreased from a mean of 22 after fertilization to one by the late embryo stage. Recently hatched protolarvae ranged from 4.7 to 5.6 mm total length and had six to seven and 28 to 31 postanal myomeres. The ratio of preanal length to total length increased as the anus migrated posteriorly during the metalarval phase; preanal myomere counts increased while postanal counts decreased. Pectoral anlages were present at hatching. By 8.0 mm, the base of the second dorsal and anal fins began to develop, and fin ray anlages were present in the caudal fin. Pelvic fin anlages appeared by 10.3 mm and all median fin rays were visible by 11.3 mm. The first dorsal fin developed between 11.3 and 15.5 mm. Metalarvae transformed into juveniles between 15.5 and 20.1 mm. Atherinid eggs were distinguished from those of other families, except the cyprinodonts, by the presence of attachment filaments. Atherinid larvae were distinguished with larval-fish keys. Identification of brook silverside eggs and larvae was based on systematic analysis and the absence of other atherinids. Species similar to brook silversides are discussed. Geographical comparisons of brook silverside eggs, larvae, and juveniles revealed differences in the number of attachment filaments, larval pigmentation, metalarval and juvenile myomere counts, and the number of first dorsal spines.