The endangered St. Francis Satyr (Neonympha mitchellii francisci) is a small sedentary butterfly and one of the rarest in North America. Our study examined various quantitative aspects of this butterfly's biology, including the distributional range, habitat associations, population size and trends, demographic parameters and spatial aspects of population structure. The range of N.m. francisci distribution is restricted to DoD lands at Ft. Bragg, North Carolina, where the butterfly utilizes wetland habitats, predominantly those that have previously been impounded by beaver. In situ habitat associations and captive rearing experiments indicate that multiple sedges in the genus Carex, particularly C. mitchelliana, may be important larval food plants. Subpopulation estimates range between 49–739 individuals at any one site, while cumulative population estimates range between 700–1400 individuals for all accessible areas on Ft. Bragg. Habitats occupied by N.m. francisci are frequently subject to burning or flooding and thus butterfly subpopulations are extremely dynamic, fluctuating in response to these disturbances. This regular disturbance regime dictates that dispersal is necessary for population persistence. Several inter-colony movements were measured during capture-recapture studies and we observed both subpopulation extinctions and colonization of new habitat through the period of our studies. Conservation of N.m. francisci depends on accommodating unique aspects of its populations, including its dependence on beaver and its multi-tiered metapopulation structure.