Blunt-nosed Leopard Lizards (Gambelia sila) are federal- and state-endangered lizards endemic to San Joaquin Desert habitat in central California. As with many endangered species, not all life-stages are equally understood. Most studies of G. sila focus on adults during the spring reproductive season, due to challenges accessing other stages (both biological and regulatory). In 2020, Fresno Chaffee Zoo received emergency permission to create a G. sila breeding colony for Panoche Plateau in the hopes of repatriating offspring and restoring this isolated population. An auxillary benefit of this colony is that it provides unprecedented access to G. sila during their more elusive life-stages, such as hatchlings during their first fall. We report on a suite of early-life traits measured in captive-reared G. sila (N = 152) including primary sex ratio, growth rate, symmetry, and thermal preference. We then compare these values to the limited observations available for wild animals in the field. Our results confirm that our incubation and rearing conditions produce G. sila with traits similar to those observed in the wild and provide new details about the natural history of this unique and endangered species.