Suicide is a complex global health problem with consequences extending far beyond the estimated annual 800,000 fatalities. According to World Mental Health Surveys, the lifetime prevalences of suicidal ideation, plans, or attempts are 9.2, 3.1, and 2.7 %, respectively. There are somewhat different patterns among nations regarding who are at risk and factors contributing to this risk. An understanding of the epidemiology of suicide and suicidal thoughts and other suicidal behaviors, namely the pattern of their distribution in populations and the factors which could be attributed to their occurrence, provide an insight into those at risk for whom preventive efforts may be targeted. Concepts, sources of epidemiological data, and key findings are presented in this chapter.