A captive population with seven snails was established in 1997 in the captive-rearing facility at the University of Hawai’i at Ma¯noa as a hedge against extinction. Following this constricted bottleneck, the population increased substantially from 1997 to 2009, reaching over 600 individuals, but is now in a Reversine five-year decline for unknown reasons. In this study we examined correlations between heterozygosity and several fitness measures including juvenile survival, survival to sexual maturity, and fecundity, and considered trends in the inbreeding coefficient over generations. We also compared genetic variation in wild A. lila with the captive population to provide long-term management recommendations. Declining measures of fitness and a loss of allelic diversity in a captive population of A. lila raise concerns about the probability of extinction due to synergistic interactions between demographics and genetics. Species recovery appeared possible following the severe bottleneck at the founding of the captive population, given population growth prior to 2009. However, in recent years mortality sharply increased and less than a third of the population remains. Declining fecundity and survival to maturity continue to hinder population recovery. Captive population allelic richness declined significantly over time, and is now lower, though not significantly so, in captive snails than in wild snails. A loss of allelic richness may interact with a number of other factors leading to the observed fitness declines in this captive population. Loss of genetic diversity is associated with an increased risk of mortality from multiple stressors, including infection. Individuals with increased homozygosity may lack advantages conferred by heterozygosity. Alternatively, the limited number of breeders in a small population increases the chance for alleles to be identical by descent, leading to an increase in homozygosity for deleterious recessive alleles, such as those that might make individuals more susceptible to disease or environmental stress. In laboratory chambers, where conditions were designed to minimize stress, fitness differences may not have been observed prior to 2009 if effects of deleterious alleles or a lack of heterozygote advantage were masked under benign conditions. Consequently, if a stressor was introduced in 2009, it may have revealed deleterious alleles or a lack of heterozygote advantage in the captive population, resulting in differential survival. If a population survives a stressful event, such as exposure to a pathogen, it may in fact lower the inbreeding coefficient, as was observed in this study following the 2009 decline. Several potential stressors that may be responsible for the captive population decline have been examined. Density effects on fecundity were tested in A. lila and determined to be nonsignificant. Transmission electron micrographs of tissues from recently deceased snails were examined, and determined to be without microsporidia, which caused the extinction of another species of land snail kept by captive propagation.