Knowledge of an animals movement are essential for a sound understanding of its natural history and ecology. The lemon shark, Negaprion brevirostris, uses the shallow water of Bimini, Bahamas, as nursery grounds. Newborns occupy a relatively small area and as the sharks grow, the size of their home range increases. However, the rate and proportion at which lemon sharks’ home range expands is unknown. Ultrasonic transmitters, with a life expectancy of up to 18 months were surgically implanted in 28 sub-adult lemon sharks. Tagged sharks were tracked from small skiffs around the clock. Shark positions were taken at regular intervals with a hand held GPS. Between November 1992 and August 1995, close to 12,000 position fixes were collected; the most extensive tracking record for any elasmobranch. Home range size and habitat diversity increased with body size. Home ranges overlapped and aggregations of up to at least 25 individuals occurred, suggesting that lemon sharks are not territorial. Sub-adult lemon sharks appeared to be site-attached and remained mostly in shallow water close to the islands, although more suitable habitats were readily available. Sub-adult lemon sharks had distinct night and day centers of activity. This pattern may be related to feeding or refuging. Lemon sharks initially captured on the western side of the lagoon at night moved eastward at dawn and westward at dusk, whereas individuals captured on the eastern side of the lagoon did not appear to have such a well defined diel pattern. These pattern variations may be related to the locations where the sharks were born.