Compilation and analysis of geographic distributions of Antillean bat species reveal two overall distribution patterns in Greater Antillean bats. In the first, found among most of the earliest known bat colonizers of the Antilles, Cuban and Hispaniolan bats have a close taxonomic relationship, whereas Jamaican and Puerto Rican bats are more distantly related. This pattern supports a limited vicariance model for early Antillean colonizers, or possibly a dispersal model modified to take into account mid-Tertiary geography. In the second, found among more recent bat colonizers, species accumulate in the western Antillean islands of Cuba and Jamaica, with limited dispersal eastward. The second pattern supports a dispersal model modified to take into account Pleistocene climatic cycles. IN RECENT YEARS, three approaches to explain the presentday distributions of Antillean organisms have become prevalent: the dispersal theory, the vicariance theory, and the ecological determinism theory. Proponents of the dispersal theory (Simpson 1956, Koopman 1958b, Terborgh 1973; Pregill 1981, to name a few) argue that overwater dispersal can account completely for observed present-day distributions, although habitat of the island in question also will affect whether a potential colonizer is successful (i.e., ecological determinism). With the increasing acceptance of plate tectonics in the last 20 yr, explanations for present-day distributions have been formulated that take into account the complex geological history of the Caribbean basin (vicariant theories of zoogeography; see Rosen 1975, MacFadden 1980). Unfortunately, adherents of one or the other approach often reject summarily the possible involvement of other factors. We have compiled herein an extensive and exhaustive list of distributions of bat species of the Antillean islands. The purpose of this paper is to test the relative importance of dispersal and vicariance as they may apply to Greater Antillean bat species. To accomplish this, we examine the distributions, attempting to detect generalized patterns of distribution. We then attempt to evaluate the importance of vicariance and dispersal in producing the patterns. GEOLOGIC HISTORY OF THE CARIBBEAN.-Several theories account for the formation of the Greater Antilles (see Molnar & Sykes 1969, Malfait & Dinkleman 1972, Meyerhoff & Meyerhoff 1972). One view, widely accepted by vicariance biogeographers, states that an island archipelago termed the formed between Central and South America in pre-Cretaceous times (Freeland & Dietz 1971, Meyerhoff & Meyerhoff 1972, Burke et al. 1984). This island cluster included parts of what are now Jamaica, Hispaniola, Puerto Rico, the Oriente Province of Cuba (though not the rest of Cuba), and various other islands now submerged. The proto-Antilles remained stationary while the North American and South American plates moved westward (Jordan 1975), thus bringing the Caribbean plate to a position just east of proto-Central Amer-