Advocates should prove that their drug testing program is a cost-effective way of protecting the public, the employer, and the employee. Better methods of testing and criteria for identifying impairment need to be developed. If health, safety, productivity, performance and cost-effectiveness are criteria, testing for marijuana should have a very low priority. Alcohol has a greater adverse effect on health, safety, and performance than all of the other drugs. Adequate personnel, procedures, and instruments are available for testing for alcohol, and the results can be satisfactorily interpreted. After testing for alcohol it would be efficient to test for other drugs in the following order: antidepressants, opiates, propoxyphene, barbiturates, and antihistamines. These drugs can impair performance. (Author abstract)