This research involves a systematic analysis of recently collected data pertaining to the enforcement of drug laws in several large American cities. The data to be analyzed include the following: (1) two statistical files developed by retrieving data from police, prosecutorial and judicial records in ten American cities during 1971 and 1972. These data provide a detailed description, from detection to disposition, of over 3,000 marihuana and 5,000 nonmarihuana drug arrestees; (2) a similar file of Federal drug arrests conducted by the Bureau of Narcotics and Dangerous Drugs, Department of Customs, Department of Treasury and Department of Justice; (3) two national surveys of illicit drug use, attitudes about such use, and attitudes about drug law enforcement and judicial process in 1971 and 1972; (4) documentary and interview material describing formal and informal drug law enforcement policy among police, prosecutorial and judicial agencies in the ten jurisdictions. The analytic objective of this research is to combine these four sets of data as an approach to answering three general questions: (1) What are the conditions, legal and extralegal, under which persons are detected and apprehended for drug offenses, (2) what are the conditions which determine dismissals, convictions and other dispositions, and (3) do drug laws, their enforcement and penalty structures, deter drug use?