This chapter shifts from discussing whether or not suicide is moral to a focus on the theories of why suicide occurs. Focusing on the eighteenth century to the present, this chapter summarizes several theories of suicide and how they uniquely frame various aspects of pain and suffering that lead to suicide. These theories vary in terms of how they attribute suicide to individual and/or societal causes, with more psychodynamic approaches locating the source of suicide in internal psychological drives and sociological perspectives, like Durkheim’s, highlighting the role of societal regulation and integration as drivers of suicide. Current theories highlight the mechanisms of ideation-to-action, and how one progresses from thinking about suicide to acting on such thoughts. This segues into a discussion of the risk factors that drive suicide risk (e.g., family history, trauma, mental illness, and social isolation) as well as factors that may buffer against suicide risk (access to mental health care, coping skills, and safe environments).