The integrated model of lethal violence, which grew out of the long history of research on homicide and suicide, is a modified and extended version of Henry's and Short's theory of suicide and homicide articulated by such researchers as Gold (1958); Whitt (1968); Hackney (1969); Unnithan (1983); Huff-Corzine, Corzine, and Moore (1991); and Unnithan and Whitt (1992). The integrated model conceptualizes suicide and homicide as two alternative channels in a single stream of lethal violence. This chapter explains the definition and measurement of two synthetic variables, the lethal violence rate (LVR) and the suicide-homicide ratio (SHR), as well as their connection to the stream analogy. Further, the chapter discusses the implications that should not be, but frequently are, drawn from the stream analogy, e.g., that homicide and suicide rates are by necessity inversely related. Relevant methodological questions, such as the ratio variables issue, are also discussed. Finally, the authors propose a strategy for testing the integrated model across multiple levels of analysis, using logic derived from Gayl Ness's 1985 work on comparative cross-national research.