Population monitoring programmes and estimation of vital rates are key to understanding the mechanisms of populationgrowth, decline or stability, and are important for effective conservation action. We report, for the first time, the populationtrends and vital rates of the endangered snow leopard based on camera trapping over four years in the Tost Mountains,South Gobi, Mongolia. We used robust design multi-season mark-recapture analysis to estimate the trends in abundance,sex ratio, survival probability and the probability of temporary emigration and immigration for adult and young snowleopards. The snow leopard population remained constant over most of the study period, with no apparent growth(l = 1.08+20.25). Comparison of model results with the ‘‘known population’’ of radio-collared snow leopards suggestedhigh accuracy in our estimates. Although seemingly stable, vigorous underlying dynamics were evident in this population,with the adult sex ratio shifting from being male-biased to female-biased (1.67 to 0.38 males per female) during the study.Adult survival probability was 0.82 (SE+20.08) and that of young was 0.83 (SE+20.15) and 0.77 (SE +20.2) respectively,before and after the age of 2 years. Young snow leopards showed a high probability of temporary emigration andimmigration (0.6, SE +20.19 and 0.68, SE +20.32 before and after the age of 2 years) though not the adults (0.02 SE+20.07).While the current female-bias in the population and the number of cubs born each year seemingly render the studypopulation safe, the vigorous dynamics suggests that the situation can change quickly. The reduction in the proportion ofmale snow leopards may be indicative of continuing anthropogenic pressures. Our work reiterates the importance ofmonitoring both the abundance and population dynamics of species for effective conservation.