Control of feral borse populations (Equus caballus) on public lands is restricted to nonlethal methods. These methods can limit population growth, however, efficacy may very among populations with differing demography and social structures Characteristics of many western feral horse populations are well documented, but fewer data are available for Atlantic barrier island populations. Therefore, we monitored a population of feral horses on Cumberland Island, Georgia from 1986 to 1990, Population growth averaged 4.3% annually with a stable age structure. Mean size of bands with ≥ 1 stallion was 4.6 horses. The adult sex ratio for the population was 0.6 females: 1.0 males. About 66% of mares foaled during a given year and no juvenile females foaled. Annual survival rates averaged 61.1% for female foals. 58.8% for male foals, and 92.4% for mares. Most bands contained a dominant or codominant stallion, mares and-or juvenile females, and foals Most mares (62.5%) changed bands ≥ 1 time during our study. Bachelors represented 50.4% of stallions. These population characteristics differed from other feral horse populations. The small band size, large number of bachelors, high degree of band instability, and codominance of band stallions on Cumberland Island likely will linut the efficacy of some forms of nonlethal population control.