The Puerto Rican ground lizard (Ameiva exsul) was first documented on St. Croix, U.S. Virgin Islands in 2006. The species is native to Puerto Rico, the northern U.S. Virgin Islands, and the British Virgin Islands, and was purportedly transported to St. Croix with a shipment of goods. Ameiva exsul has since become established in a northcentral neighborhood of St. Croix, from which we collected six specimens. Analyses of their gastrointestinal tracts demonstrated they had consumed vertebrates and invertebrates. In particular we documented a Sphaerodactylus sp. gecko, and eggs of the endemic anole, Anolis acutus, as prey of A. exsul. The potential for establishment of A. exsul on offshore cays where the only populations of the St. Croix ground lizard (Ameiva polops) exist is a serious conservation concern, as it may prey on and compete for resources with this critically endangered endemic species.