Considers constructs and theories related to legalized and illicit drug use, abuse and addiction across the lifespan. Focuses on biological, psychological, social antecedents of drug use, and on biopsychosocial consequences of drug use and dependence within developmental contexts. Examines specific drug addictions and treatment approaches. Health psychology, counseling psychology, developmental psychology, neuropsychology, medicine, health education, and public health perspectives are considered. Emphasizes the interplay of the knowledge and understandings developed from these perspectives, and applies this knowledge to research and counseling practice.