An 18-year longitudinal case study of the suicide rates of students attending a large, urban, multicultural school district between 1989 and 2006 is described. The high rate of suicide (5.5 per 100,000 students ages 5-19) in the district during the period 1980-1988 led to the development and implementation of a district-wide Youth Suicide Prevention and Intervention Program. The program is based on a three-tier suicide prevention model incorporating universal, selected, and indicated prevention/intervention strategies. Suicide and suicide attempt data were collected from crisis hotline reports. Since implementation of the program, a significant decrease in the suicide rate (1.4 per 100,000) was observed from 1989 to 2006. There also was a steady decline in the suicide attempt rate during this same period. This study is among the first to provide longitudinal evidence that youth suicidal behavior can be reduced potentially through school-based suicide prevention programs. (Contains 3 figures.)