TLC identification techniques well suited to large-scale screening of urine samples for drugs of abuse are presented. Chromatographic developing solvent systems are described that can differentiate: (a) drugs of abuse and their adulterants from drugs used in treatment, and (b) methadone and/or cocaine from methapyrilene, diphenhydramine, pentazocine, cyclazocine, pipradrol, propoxyphene, thioridazine, promazine, and chlorpromazine. In addition, highly reliable spraying techniques for the identification of amphetamine, methamphetamine, and phenmetrazine are suggested. The combination of sprays described here reliably detects barbiturates at relatively low concentrations. A spraying technique to differentiate methadone from cocaine is also described.