This essay explores the much-debated question regarding the extent and viability of Thomas Aquinas as a theological source for expanding Christian ethical concern for the nonhuman creation, particularly nonhuman animals. This exploration focuses on the intersection of two foundational issues in Aquinas' theological framework, nature and teleology, as well as the effects of this intersection in Aquinas' work concerning nonhuman creation. From these examinations, I suggest that Aquinas can provide significant contributions for augmenting concern for the welfare of nonhuman animals because his theological framework demands that humans preserve the natural order through conservation. However, Aquinas' ecotheological ethics of conservation is foundationally anthropocentric and only permits indirect moral concern for the nonhuman world.