An event-history analysis of the disbandings of nationally active gay and lesbian rights advocacy groups in the United States for the period 1945–98 is presented. Specifically, the hypothesis (which comes from population-ecology theory) is tested that the survival prospects of gay and lesbian rights interest groups are related non-monotonically to the number of groups in the population (i.e., density). The statistical analyses presented support the hypothesis: as density rises from near zero to high, the death rate first decreases but eventually increases. Several other hypotheses are also tested, and among the findings is the following: the survival prospects of gay and lesbian rights interest groups are related non-monotonically to group age – as group age increases, a group's probability of death first rises but then decreases.