Four syntopic assemblages of parthenogenetic lizards were compared for differences in body size at which reproductive maturity is attained and mean clutch size: 1) Aspidoscelis flagellicauda and A. exsanguis from the vicinity of San Francisco Hot Springs (type locality of A. flagellicauda), Catron and Grant counties, New Mexico; 2) A. flagellicauda and A. sonorae from the vicinity of Oracle, Pinal County, Arizona (type locality of A. sonorae); 3) A. sonorae (3 color pattern classes) from the vicinity of Cochise Stronghold, Cochise County, Arizona; and 4) A. sonorae (2 color pattern classes) from the vicinity of Parker Canyon Lake, Cochise County, Arizona. Reproduction begins at a smaller body size in A. exsanguis (61 mm SVL) than in A. flagellicauda (70 mm SVL). This results in a higher population density in A. exsanguis, despite the larger mean clutch size in A. flagellicauda (3.7 vs. 3.3 eggs). Aspidoscelis sonorae and A. flagellicauda, although morphologically distinguishable, were not significantly different in size at reproductive maturity or mean clutch size, which was also true for the color pattern classes of A. sonorae.