In this thesis, the life history and population biology of an endemic and declining California butterfly, Speyeria adiaste clemencei (Comstock, 1925) is described from Chews Ridge, Monterey Co., CA. S. a. clemencei can be successfully reared on commercially available Viola spp., facilitating captive rearing for restoration. Larvae of S. adiaste can be distinguished morphologically from sympatric S. callippe and S. coronis larvae based upon coloration of the dorsal and dorsolateral scoli, head capsule coloration, and coloration of setae, facilitating identification in the field. Adequate access to nectar sources throughout the flight period, especially during drought years, as well as host plant density and distribution, are critical aspects for maintaining viable S. a. clemencei populations. To gain a better understanding of its population biology, three seasons of weekly Pollard walk counts and two seasons of mark recapture (MR) were conducted. The population declined during the study period, which may be associated with decreasing rainfall. MR estimates were very strongly correlated with weekly Pollard walk counts. Differences in habitat use between the sexes were observed, with males showing a slight preference for ridge over meadow plots, whereas females preferred meadow plots containing Viola host plants. Analysis of survival and dispersal indicated this species is relatively short-lived with low dispersal ability, two traits associated with its life history that have important implications for re-colonization dynamics and population structure.