This report describes the implementation of the MRSDT programs and their impacts on students in terms of student-reported substance use and other outcomes. The evaluation found that students subject to MRSDT reported less substance use than comparable students in high schools without MRSDT. The MRSDT program, however, had no "spillover effect" on the substance use reported by students who were not subject to testing, and the program had no effect on any group of students' reported intentions to use substances in the future. Contrary to concerns raised about the negative consequences of the MRSDT program, it had no effect on the proportion of students participating in activities subject to drug testing or on students' attitudes toward school and the perceived consequences of substance use. There was some evidence that the impacts of the MRSDT program were related to the ways in which the programs were implemented. Both testing for a larger number of substances and testing for alcohol and tobacco were significantly correlated with lower substance use in the treatment schools compared to the control schools; however, it was not possible to distinguish between these two sets of factors because districts that tested for a larger number of substances were also those districts that tested for alcohol or tobacco. Program goals are to identify students with substance-use problems for referral to appropriate counseling treatment services, as well as to deter students from substance use. Under the MRSDT program, students and their parents sign consent forms agreeing to the students' random drug testing as a condition of participation in athletic and other school-sponsored competitive extracurricular activities. Extensive tables, 32 references, and appended study instrument and supplementary information