There has been a lack of debate between and frameworks for theories of the causes of poverty. This essay proposes that most theories of poverty can be productively categorized into three broader families of theories: behavioral, structural, and political. Behavioral theories concentrate on individual behaviors as driven by incentives and culture. Structural theories emphasize the demographic and labor market context, which causes both behavior and poverty. Political theories contend that power and institutions cause policy, which causes poverty, and moderates the relationship between behavior and poverty. I review each theory’s arguments, contributions and challenges. Further, I explain how to integrate, classify studies into, and distinguish between theories. Ultimately, I argue that poverty research would benefit from more explicit theory and theoretical debate, as well as greater interdisciplinarity and integration between studies of the U.S., rich democracies, and developing countries.