Motivational Interviewing (MI) to reduce alcohol and marijuana-related driving events among incarcerated adolescents was evaluated. Adolescents were randomly assigned to receive MI or Relaxation Training. Follow-up assessment showed that, as compared to RT, adolescents who received MI had lower rates of drinking and driving, and being a passenger in a car with someone who had been drinking. Effects were moderated by levels of depression. At low levels of depression, MI evidenced lower rates of these behaviors; at high levels of depression, effects for MI and RT were equivalent. Similar patterns were found for marijuana-related risky driving, but effects were nonsignificant.