Current understanding of the mode and tempo of evolutionary divergence within the major groups of terrestrial vertebrates of the Galápagos Archipelago is summarized from three perspectives: (1) the number and relative timing of introductions for each group; (2) the influence of historical factors and present-day population demography of patterns and amounts of genetic diversity; and (3) possible mechanisms of adaptive radiation, or macroevolution, within the tortoise and finch groups.Native and introduced rats, lava lizards, geckos, and iguanas most likely had more than one episode of introduction from already differentiated mainland stocks. The finches and tortoises appear to have originated from but a single respective radiation. The influence of these differences in invasion histories is clearly evident in patterns of within-island genetic biochemical diversity and between-island or between-species differentiation. It is argued that much of the pattern of within-species geographic differentiation in genetic characters results from the temporal history of populations, including the amount of migration between islands, as well as differential selection pressures. Major morphological differentiation within both the finch and tortoise radiations has occurred with minimal change at structural gene loci. Studies of, for example, developmental heterochrony and character heritability analyses are needed to understand this apparent paradox.