Scientific goals: (1) To assess, cross-sectionally at baseline, differences in stress, social stability, and mental and physical health among three main neighborhood-matched groups of current opioid/stimulant users, current marijuana users, and nondrug users; (2) to assess, longitudinally, mediators of 12-month changes in drug-misuse status in the same three groups; (3) to provide neighborhood-matched control groups of non-drug-using individuals, Unclassified/former drug users, and current opioid/stimulant drug users not seeking treatment for our ongoing environmental studies of individuals in drug treatment; (4) to explore the possible role of genetics and its interplay with environment in regards to drug use initiation, addiction, and treatment seeking among the study groups, and (5) to assess EMA reports of drug use and psychosocial stress as well as real-time environmental risk exposure in a non-treatment seeking and/or nondrug using population and compare to our ongoing environmental studies of individuals in drug treatment,