Natural law theories are committed to the idea that there is a set of intrinsically valuable goods that define a flourishing human life. These goods include such things as life, knowledge, friendship, work and play, and on at least one version, the natural world. They form the basis for developing fundamental moral principles or rules that serve as a guide for decision making. If climate change threatens these goods, natural law theorists have reason to argue that human beings ought to arrive at sustainable solutions. In this chapter, I discuss the general ideas grounding natural law theory and the components of individual accounts. I go on to argue that three goods in particular are threatened by climate change: at least some of the goods that constitute or enable human flourishing; the natural environment; and the common good. All natural law theorists make connections between the basic goods and human well-being. One theorist includes the natural environment on his list of basic goods while another includes the common good. Thus, insofar as climate change poses a threat to these goods, natural law theorists ought to address climate change.