The effectiveness of mandatory-random student drug testing: a cluster randomized trial.

Purpose: This article presents findings from the largest experimental evaluation to date of school-based mandatory-random student drug testing (MRSDT). The study tested the effectiveness of MRSDT in reducing substance use among high school students.

Methods: Cluster randomized trial included 36 high schools and more than 4,700 9th through 12th grade students. After baseline data collection in spring 2007, about half the schools were randomly assigned to a treatment group that was permitted to implement MRSDT immediately, and the remaining half were assigned to a control group that delayed MRSDT until after follow-up data collection was completed 1 year later, in spring 2008. Data from self-administered student questionnaires were used to compare rates of substance use in treatment and control schools at follow-up.

Results: Students subject to MRSDT by their districts reported less substances use in past 30 days compared with students in schools without MRSDT. The program had no detectable spillover effects on the substance use of students not subject to testing. We found no evidence of unintentional negative effects on students' future intentions to use substances, the proportion of students who participated in activities subject to drug testing, or on students' attitudes toward school and perceived consequences of substance use.

Conclusions: MRSDT shows promise in reducing illicit substance use among high school students. The impacts of this study were measured for a 1-year period and may not represent longer term effects.