The study shows that drug testing is a promising drug prevention strategy. Based on written student surveys, 58 percent of the principals reported that student drug use decreased over the study period; 42 percent reported that student drug use remained the same; there were no reports that student drug use increased. For 41 percent of the schools, drug tests that showed positive results decreased 41 percent, and positive test rates remained the same for 56 percent of the schools; positive tests increased for 3 percent of the schools. Testing limited the effects of peer pressure on drug use in 91 percent of the schools. Student participation in athletic programs increased in 46 percent of the schools and remained the same in 54 percent. It did not decrease in any of the schools. Student participation in extracurricular activities increased in 45 percent of the schools and remained the same in 55 percent of the schools. It did not decrease in any of the schools. All of the principals reported that random drug testing did not have a negative impact in the classroom. For 91 percent of the schools, the cost of drug testing was $30 or less per test. For 63 percent of the schools, it was $20 or less per test. These findings support the belief that random drug testing, used in conjunction with other components of a comprehensive program for preventing and treating substance abuse, can be a useful tool in drug abuse prevention. The study compared the results of an April 2005 survey of 65 Indiana high school principals (56 responded) with data collected from the same schools in a 2002-2003 survey.