Longitudinal trajectories of marijuana use from adolescence into adulthood were examined for adverse life-course outcomes among African-Americans and Puerto Ricans. Data for marijuana use were analyzed at four points in time and on participants' personality attributes, work functioning, and partner relations in adulthood using growth mixture modeling. Each of the three marijuana-use trajectory groups (maturing-out, late-onset, and chronic marijuana-users) had greater adverse life-course outcomes than a nonuse or low-use trajectory group. The chronic marijuana-use trajectory group was highly associated with criminal behavior and partners' marijuana use in adulthood. Treatment programs for marijuana use should also directly address common adverse life-course outcomes users may already be experiencing.