Historically, the majority of people with substance use disorders in the US has been under age 50. This trend is changing as baby boomers with record high prevalence rates of substance disorders, enter their 50s and 60s, and their demand for treatment is expected to double for the second time by 2020. Consequences of addiction and HIV risk behaviors are expected to interact with vulnerabilities associated with natural aging. While rates of long-term recovery increase with age, many will continue to relapse and interact with treatment systems lacking in age-appropriate services. An empirical basis is needed to inform service development and delivery. Few long-term studies of individuals with chronic addiction and treatment histories exist;even fewer elucidate the interface between chronic addiction, HIV risk behaviors and aging. Preliminary analyses from a recent longitudinal study (Scott &Dennis 2009) indicated that among 348 adults who reported multiple sexual partners, 299 (86%) stopped engaging with multiple partners during one or more quarters (over 21 months), but 297 (85%) subsequently re-engaged at some point with multiple partners. Among the 515 adults who reported unprotected sex, 402 (78%) stopped during one or more quarters, but 467 (91%) subsequently re-engaged in unprotected sex. Among the 114 adults who reported needle use, 106 (94%) stopped during one or more quar-ters, with 43 (38%) subsequently reinitiated needle use. Moreover 2/3rds of those engaging in these high-risk behaviors in any given quarter were not immediately willing to enter treatment. Thus, as is the case for sub-stance use in general, this suggests the need to better understand the apparent cyclical nature of HIV risk behaviors over time. The proposed study targets this gap by capitalizing on a previous NIDA-funded longitudinal study that re-cruited 1,326 people presenting to publicly funded substance abuse treatment between 1996 and 1998 and re-assessed 9 times through 2007 (90%+ retention/wave). The original gender-balanced sample consisted largely of ethnic minority members with chronic histories of polysubstance use including cocaine (64%), alcohol (44%), opioids (41%), or marijuana (14%). At intake, the mean age was 35 years (4% 50+), at 9 years it was 44 (18% 50+), at the start of the proposed study it will be 49 (42% 50+) and at the close 54 (53% 50+). This project will extend the original study by adding annual interviews at 14, 15, 16, 17, and 18 years post intake to establish one of the longest and largest treatment cohort studies of its type to date. The cohort[unreadable]s comprehensive history, captured in earlier waves, paired with new prospective information, offers a cost-effective and rare opportunity to identify factors to help minimize the burden of aging on the substance use and heath fields. Study aims are to: 1) Determine if there are age-related changes in the predictive value of factors expected over time to in-crease (including age of first use, number of sober friends, treatment received) and decrease (including severi-ty, mental distress, legal involvement, HIV risk behaviors) the likelihood of initiating/maintaining abstinence over the next 12 months;(2) Determine if there are age-related changes in the predictive value of factors expected over time to increase (e.g., prior abstinence, being female, self-help engagement) and decrease (e.g., number of prior treatment episodes, homelessness, and number of arrests, HIV risk behaviors) the likelihood of maintaining abstinence another 12 months;(3) To test whether there are age-related changes in the predictive value of variables expected over time to decrease (e.g., loss, grief, HIV risk behaviors, functioning, disability) and increase (e.g., activity level, quality of life, social support) the time from 3 years of abstinence to late stage relapse, (4) To evaluate whether there are age-related changes in the impact of the cumulative pattern of re-covery on future critical positive and negative health outcomes (e.g., quality of life, functioning, disability, death), (5) To evaluate whether there are age related changes in the impact of the cumulative pattern of HIV risk behaviors on future HIV status and other health outcomes.