For a long-standing survey of reservation Indian youth, each year the author selects five to seven tribes that are geographically and culturally representative of Indian youth across the country. When reporting on drug-use prevalence rates, the study aggregates across 2- or 3-year periods to reduce sampling bias. Data are presented in this report to show the percentage of reservation Indian 7th-12th graders who report lifetime use of drugs for 1975-1990. One overall trend is evident: for several of the more commonly used drugs there was a dramatic increase in use by Indian youth between 1975 and 1981, and there has been a gradual decline since them. This pattern is clear for marijuana, inhalants, and stimulants. Additional data provided in this chapter provide support for a general decline in drug use since 1981 among adolescents. This same pattern holds true for youth in general in the United States. Since 1977, however, the number of high-risk drug users (those who end up in treatment or in the hospital) has not changed. This suggests that members of this group cannot be reached by the usual prevention efforts. 2 tables and 1 figure