Several species of lizards exhibit significant annual variation in reproductive traits; however, most work in this area focused on populations from temperate latitudes or low to medium elevations. We examined annual variation in litter size, neonate size, and relative litter mass in a high elevation (4200 m) population of the viviparous lizard, Sceloporus bicanthalis from the Volcano Nevado de Toluca, México. We found little evidence for annual variation in reproduction in this population. Female body size influenced litter size and litter mass. Relative litter mass in this population (0.47) was among the highest reported for any Sceloporus and may be a consequence of a nearly “annual” life cycle. Mean neonate size was not affected by female SVL or litter size, suggesting it may be optimized in this population.