Testing hypotheses on the drivers of clade evolution and trait diversification provides insight into many aspects of evolutionary biology. Often, studies investigate only the intrinsic biological properties of organisms as the causes of diversity, however extrinsic properties of a clade’s environment, particularly geological history, may also offer compelling explanations. The Andes are a young mountain chain known to have shaped many aspects of climate and diversity of South America. The Liolaemidae are a radiation of South American reptiles with over 300 species found across all biomes and with similar numbers of egg-laying and live-bearing species. Using the most complete dated phylogeny of the family, we tested the role of Andean uplift in the biogeography, diversification patterns, and parity mode of the Liolaemidae. We find that the Andes has promoted lineage diversification and acted as a species pump into surrounding biomes. We also find strong support for the role of Andean uplift in boosting the species diversity of these lizards via allopatric fragmentation. Finally, we find repeated shifts in parity mode associated with changing thermal niches, with live-bearing favored in cold climates and egg-laying favoured in warm climates. Importantly, we find evidence for possible reversals to oviparity, an evolutionary transition believed to be extremely rare.