It is diffi cult to imagine anything more interesting to biologists and advanced naturalists than understanding origins of the diversity of reproductive patterns among lizards. Among species, some lay eggs, some produce many offspring in a single reproductive episode whereas others produce few offspring, and some make no nest at all whereas others construct nests and attend eggs until hatching. Most species are oviparous and among those, some lay eggs immediately after they are shelled, whereas others retain eggs for extended periods before oviposition. Many species are livebearing and viviparity has arisen multiple times within squamates. Some reproduce sexually and others asexually. For some the sex of embryos is determined genetically and for others sex is determined by developmental temperature. Differences in reproduction listed above are but a small sampling of the many fascinating aspects of lizard reproduction that have caught the attention of biologists. Moreover, trying to understand how and why suites of reproductive traits vary has resulted in identifi cation of new conceptual issues in evolutionary ecology.