Historical bottlenecks, habitat fragmentation, and small populations resulting in decreased heterozygosity typify conservation concerns of globally threatened carnivore populations. We monitored the endangered Asiatic lion (Panthera leo persica) by radiotelemetry (n = 20), individual profiles (n = 55 adults and 91 cubs from 38 litters), and observed mortalities (n = 88) to estimate survival, mortality causes, interlitter interval, and litter size in the Gir Forest region of Gujarat, western India, between 2000 and 2010. Lions increased from about 177 in 1968 to about 411 by 2010 with r = 0.022 ± 0.001 SE. The male : female ratio was 0.63 ± 0.04 SE, whereas the cub : adult lioness ratio was 0.37 ± 0.02 SE. Mating peaked in winter and birth peaked in late summer. Average litter size was 2.39 ± 0.12 SE. Interbirth interval was 1.37 years ± 0.25 SE (n = 7 lionesses) and was higher (2.25 ± 0.41 years) when cubs of the previous litter survived to independence. Cub survival was 0.57 ± 0.04 SE, whereas survival from cub to recruitment age (3 years) was 51% ± 4% SE, with mortalities due to infanticides being 30% ± 7 %. Juvenile (1–2 years) and subadult (2–3 years) survival rates were 0.87 ± 0.04 SE and 0.90 ± 0.04, respectively. Average annual survival rate of adult lions (>3 years) was 0.9 ± 0.12 SE. Adult lions died primarily due to natural causes (54.5%); however, human-caused mortality was substantial (43.2%) and was likely additive to natural causes. Demographic parameters of genetically less-diverse Asiatic lions did not differ from those of African lions.