There are limited prospective data on suicide attempts (SA) during the months following treatment for substance use disorders (SUD), a period of high risk. In an analysis of the Drug Abuse Treatment Outcomes Study, a longitudinal naturalistic multisite study of treated SUDs, variables associated with SA in the 12 months following SUD treatment were examined. Participants included 2,966 patients with one or more SUDs. By 12 months, 77 (2.6%) subjects had attempted suicide. Multivariate logistic regression analyses were used to identify variables associated with SA. Variables collected at baseline that were associated with SA included lifetime histories of SA, suicidal ideation (SI), depression, cocaine as primary substance of use, outpatient methadone treatment, and short-term inpatient treatment. Male sex, older age, and minority race or ethnicity were associated with lower likelihood of SA. After controlling for baseline predictors, variables assessed at 12 months associated with SA included SI during follow-up and daily or more use of cocaine. The data contribute to a small but growing literature of prospective studies of SA among treated SUDs, and suggest that SUDs with cocaine use disorders in particular should be a focus of prevention efforts.