This medium-sized rattlesnake can be found in southern California and in Nevada. While it is more frequently found in hilly or mountainous areas with scattered rock formations, it can be found in a variety of other habitats and elevations, including moving into lower desert formations during cooler weather.

This species breeds in mid-spring and will give birth to 3-5 young.

Panamint rattlesnakes are highly nocturnal/crepuscular, being active from the time just before sundown until just a few hours after sunset. A likely reason for this behavioral pattern is the extreme conditions of the arid mountains which they live, where the daytime temps are dangerously hot but nighttime cooling temps also present a cold threat.

In 2007, the Panamint rattlesnake was elevated to its own species, Crotalus stephensi, after being a subspecies of the speckled rattlesnake, Crotalus mitchellii. This was determined through DNA and morphology, and the study concluded that this species of rattlesnake did not interbreed with the southwestern speckled rattlesnake. It's important to distinguish isolated species to further influence conservation of biodiversity!

In California, where this species shares a border with the closely related southwestern speckled rattlesnake (Crotalus pyrrhus), the two species do not overlap despite similar habitat. It is hypothesized that Panamint rattlesnakes are limited from further southward distribution by warmer climates, while C. pyrrhus is outcompeted and thus limited from further northward distribution by C. stephensi.