Correlates and predictors of suicidal ideation and substance use among adults seeking substance use treatment with varying levels of suicidality

•Suicidality rates are high among adults seeking substance use disorder treatment.•Suicidality groups differed in demographics, substance use, and health indicators.•Suicidality groups did not differ in drug/alcohol toxicology outcomes throughout treatment.•Adults with recent suicidal ideation did not maintain reductions in severity of alcohol problems at 6-months post-treatment.•Adults with past suicide attempts showed less improvement in drug use severity from post-treatment to 6 months post-treatment.