This study examined long-term effects of a school/family/community substance abuse prevention partnership intervention lead by a Midwestern school district. Previous findings suggested that the program contributed to decreased tobacco and marijuana, but not alcohol, use prior to and after implementation between 1987 and 1991. The current study examined 8th--12th grade student drug use prevalence data from 1991 and 2003 to determine whether previous program effects were sustained. With one exception, reported lifetime and monthly cigarette use decreased below 1991 levels for all grades. Lifetime and monthly alcohol use decreased below 1991 levels for most grades, a result not previously detected. While still below national rates, reported lifetime use of marijuana increased for all grades over time. The intervention was effective in reducing cigarette and alcohol use over time and in suppressing marijuana use levels below national rates; however, these gains tended to erode in later high school grades. (Contains 6 tables and 2 figures.)