OBJECTIVE: The purpose of this study was to examine the effects of age, common life transitions, treatment, and social support on outcomes 5-9 years after alcohol and other drug (AOD) treatment intake. METHOD: Participants were patients from a large outpatient AOD treatment program in an integrated health plan. There were 1,951 participants interviewed at intake, of whom 1,646 (84%) completed one or more telephone follow-up interviews at 5, 7, and 9 years. Measures included AOD use based on the Addiction Severity Index; treatment; and changes in marital, employment, and health status in the years between each follow-up. We compared participants by age group (18-39, 40-54, and >/=55 years old at intake) and examined factors (time invariant and time varying) associated with outcomes at 5, 7, and 9 years by fitting mixed-effects logistic random intercept models. RESULTS: Changes in marital, employment, and health status varied significantly by age. Factors associated with remission across Years 5-9 included being in the middle-aged versus younger group (p < .001); female gender (p < .001); not losing a partner to separation, divorce, or death (p < .001); not experiencing a decline in health (p = .021); having any close friends supportive of recovery (p < .001); and not having any close friends who encourage AOD use (p < .001). Additional predictors, including employment changes, varied by drug versus alcohol abstinence outcome measures. CONCLUSIONS: Negative life transitions vary by age and are associated with worse outcomes. Older age and social support are associated with long-term AOD remission and abstinence. Findings inform treatment strategies to enhance recovery across the life span.