The Greenhouse Frog (Eleutherodactylus planirostris) is one of the most widespread frog species in the world. Because of its high population densities, widespread distribution, and consumption of native invertebrates in some invaded sites, understanding its impacts in Hawaii is important. We analyzed stomach contents of 397 frogs from 10 study sites in Maui. Results suggest Greenhouse Frogs are active, ant-specialist predators in the leaf litter. Ants (Formicidae) were the dominant prey found in stomachs in both number and volume. Furthermore, only ants were consumed in a higher proportion than they were sampled in the environment. Because ants dominated their diets, and because all ants are nonnative to Hawaii, this means Greenhouse Frogs consumed primarily nonnative invertebrates (>80%) in the areas sampled. Although results suggest that most native taxa are not at risk from Greenhouse Frog predation, the only locations where we could currently find Greenhouse Frogs were in human-dominated lowlands, which have a lower proportion of native species. Greenhouse Frogs may consume more native species if they invade more native-dominated habitat. Alternatively, nonnative ants are known to impact negatively many native invertebrates in Hawaii, and their possible reduction through Greenhouse Frog predation could affect other species positively. Our research highlights the need to understand better the effects of Greenhouse Frog predation on both native and nonnative invertebrates in Hawaii.