This is one of the very few monographs on suicidology. The author is a sociologist by training, and the Strain Theory of Suicide has been conceptualized, tested, and supported over the past 15 years with empirical data from various samples in different populations. This is a parsimonious model accounting for suicidal behaviors from a multi-disciplinary perspective. The Strain Theory of Suicide explores the etiology of suicide and is well coordinated with previous theories of suicide, such as that of Emile Durkheim, in explaining the trajectory of suicide in the human world. The Strain Theory of Suicide not only assists people to understand why people kill themselves and to be aware of the risk and protective factors relating to suicide, but also serves as foundation for suicide prevention and intervention research and practices.