Larvae of the tropical fiddler crab, Uca thayeri , were reared in the laboratory from hatching to metamorphosis. Development consists of 5 zoeal stages and a megalopa. At a constant temperature (25 degree C), each zoeal stage lasts 4 to 5 days, and ca. 10 to 14 days is required for the megalopa. Somewhat more than one month is needed for the whole process. A detailed description of larval morphology is given and compared with those of eight other Uca species, for which partial or complete descriptions are available.