RSA refers to a methodology that uses a combination of several qualitative and quantitative data collection techniques; it draws on a variety of data sources to arrive at an understanding of the nature, extent, and trends regarding certain health and social problems (such as drug abuse) and of structures and services that do or do not exist, so as to develop ways of addressing the problems. In the course of an RSA applied to drug abuse, use is made of existing secondary data, such as number or quantity of drug seizures, arrest figures, changes in drug prices, changes in specific types of crime associated with drug abuse, number of callers to anonymous help lines, number of people seeking treatment, number of deaths resulting from drug abuse, etc. Primary data are obtained in the course of focus group discussions; from key informants; and by means of direct interviews with drug abusers in the streets, in treatment centers, and in prisons or other correctional facilities. In addition to presenting the general principles of RSA applied to drug abuse, this report provides examples from the various RSAs contracted by the United Nations Office for Drug Control and Crime Prevention. 9 references