This chapter outlines developments in attribution theory that the authors regard as the social-psychological underpinnings of the integrated model of suicide and homicide. Drawing on the stress-diathesis model of hopelessness depression; attributional studies of self-blame and other-blame, as well as of guilt, shame, and anger; this chapter suggests that, at the individual level, both suicide and homicide result from a combination of negative life events (frustrations, stress) with attributional styles that locate blame either in the self (suicide) or in others (homicide). In this sense, suicide parallels clinical depression while homicide has elements in common with paranoia. The authors suggest that individuals who kill themselves and those who murder others should make causal attributions at opposite ends of the paranoid-depressive existential continuum, but both should find themselves in the grip of pervasive pessimism (hopelessness) about their prospects for the future. The chapter then identifies some of the situational, cultural, and structural sources of the attribution of blame, including social class, social isolation, economic development, and religion.