The reproductive cycle and cycle in fat body mass are described for male and female Sceloporus pyrocephalus taken from the Municipio de Tejupilco, state of México, México. Males reached sexual maturity at 50.0 mm snout–vent length (SVL); females reached sexual maturity at 47.0 mm SVL. Testis of males began to increase in size in early April, maximum testis mass occurred during May through October, and testis mass decreased abruptly in November and December. Maximum testicular growth was associated with increased temperature, photoperiod, and precipitation. This is an oviparous species. Enlarged vitellogenic follicles first appeared during early May in females. Females contained oviductal eggs from May to September. Vitellogenesis, follicular growth, and egg production were associated with increasing photoperiod and precipitation but not with temperature. From a sample of 21 females with oviductal eggs, 13 (61.9%) had two clutches, and eight (38.1%) had a single clutch. Mean clutch size was not correlated with female SVL.