We radio-tagged Black Rails (Laterallus jamaicensis) and located active nests at two sites in Florida from May 1992 to August 1996. We collected telemetry locations from 1–6 h daily during the egg-laying and incubation period. Home range estimates differed significantly between sexes; males used 1.3 ha and females used 0.62 ha. Nests were found at all stages of egg-laying and incubation using radio telemetry and visual nest searching. Nests were located during each month from May through August. Nests were constructed over moist soil in low (≤1 m) dense herbaceous vegetation. Black Rails preferred nest sites near hyper-saline patches of bare sand. The Mayfield estimate of nesting success was 43%, nest failures were caused by flooding and predation. Imported red fire ants (Solenopsis invicta) were observed constructing mounds under three nests and killed one hatchling before it emerged from the egg. Water level and hydrology may have the greatest impact on nest-site selection and nesting success of Black Rails.