Patterns of drug use on college campuses are studied. An increasingly secular society has resulted in more private drug use for nonmedical purposes. Characteristics of drug diffusion are presented. Reasons for becoming committed to drugs are frequently different from those which promote experimentation with drugs. Reasons why people use drugs are organized in terms of the functions drugs serve. Drugs may serve psychopathological functions. As such they may reduce psychological pain, provide partial resolution of maturational difficulties and aid in the reduction of intimacy in human relationships. Drug use in terms of interpersonal pathology is studied as is the problem of ethnocentrism in groups of drug users. Other aspects of drug use are examined. These functions include the use of drugs as: (1) a source of mystical and religious feeling, (2) a creative and esthetic experience, (3) an escape from the constant obligations of society or from computer reality, (4) a way to induce feelings of invulnerability, (5) a reflection of the new morality, (6) a mild form of rebellion, and (7) simply as a source of fun. (PS)