The reproductive ecology of the lizard Tropidurus catalanensis (Tropiduridae) from two sites of the subtropical region of southern Brazil was described. In Alegrete municipality, 315 individuals were sampled over a period of 12 mo (2007–2008) to analyze the reproductive biology of males and females. In Santa Maria municipality, the identification of the oviposition sites and monitoring of clutches were performed over a period of 26 mo (2006–2009). Mature individuals of both sexes were found throughout the year, with a strong peak during the mating season (spring). The reproductive cycle of males and females from the studied population was seasonal. The oviposition period extended from spring to early summer and recruitment occurred from late spring to early autumn. There was a trend toward nesting in rocky crevices and soil cavities; communal nests were also recorded. Females reached sexual maturity at larger sizes than males. The development of male secondary sexual characters is probably associated with sexual identification and social hierarchy. Lipid accumulation in males and females was indirectly related to reproductive activity, reaching higher levels during the season with lower food availability (autumn). There was no relationship between environmental variables and the reproductive cycle of males and females.