Two populations of the Desert Iguana, Dipsosaurus dorsalis lucasensis, from the Cape region of Baja California and from Cerralvo Island, were compared meristically and colorimetrically. The Cerralvo Island specimens were found to be significantly smaller in size, and possessed fewer midbody scales than specimens from the Cape peninsula. The insular specimens were also typically more melanic with a less distinct lateral reticulate pattern. These findings suggest that the Cerralvo Island population of lucasensis possibly diverged from the peninsular stock earlier than other insular populations of that subspecies, supporting the idea that Cerralvo is a much older Gulf island than others inhabited by the species.