The epidemiologic data evaluated are longitudinal data, demographic data, cross-cultural data, and data on high-risk groups and relative risk. Examination of the epidemiology of U.S. suicide rates from 1900 to 1980 reveals that the major shifts in rates are due to socioeconomic factors such as war, population shifts, and the economy. The shifts in rates due to such socioeconomic factors occur invariably throughout the century for all age, race, and sex groups. The concepts the chapter uses to explore suicide intervention and prevention involve epidemiologic concepts of prevention (primary, secondary, and tertiary) and groups at high risk. Primary prevention refers to efforts to prevent suicide in the general population. Secondary prevention focuses on persons who have attempted suicide, and tertiary prevention involves intervention in family and school following a suicide. Five issues are considered regarding primary prevention in the general population: developmental aspects (public education), training of professionals and paraprofessionals in suicidology, agents, suicide prevention centers, and population changes and cohort effects. The discussion of prevention and intervention with high-risk groups focuses on psychiatric patients and those with high-risk factors (unemployed, single or divorced, those suffering recent losses, whites, males, older persons, and adolescents). Eight suggestions for future research are offered. 61 references.