This review examines recent research on the psychological effects of marijuana. The article contains material on potency, research problems, use patterns in the United States, and expectancy, as well as a review of research on acute effects, including psychosis, toxic delerium, acute anxiety, and brain damage. Nonacute effects are also examined, with material on studies of amotivational syndrome, intellectual functioning, memory, sexual activity, and driving. Research on marijuana's relationship to other drugs and to criminal behavior is also evaluated. Implications for counselors are discussed. Counselors are urged to help provide accurate information to users and to encourage an informed‐decision approach. The significance of marijuana use to value and life‐style choice and the counselor's role in considering marijuana law changes are evalua