Eight species of lizards are reported from the islands of Rarotonga and Mangaia with comments on their distribution, ecology, reproduction, and variation. Particular attention is given to systematic problems in the genus Cryptoblepharus and pattern polymorphism in Emoia cyanura. Emoia trossula, recently described from Fiji, is reported for the first time in the Cook Islands. Historic and zoogeographic evidence suggests that most species of lizards arrived on Rarotonga and Mangaia in Polynesian voyaging canoes within the past 1000 years, although Gehyra mutilata and Hemidactylus garnotii may have arrived by incidental boat or air transport in the past several decades.