Objective To identify demographic, diagnostic, and personality factors that predict treatment dropout in a sample of outpatients with clinically significant suicidal ideation. Method A total of 287 adult outpatients at elevated risk for suicide completed self‐report measures of demographics, suicidal and depression symptoms, and personality characteristics at treatment intake. Clinician‐assessed psychiatric diagnoses and ratings of overall functioning also were collected. Results Lower overall functioning (odds ratio [OR] = .947; 95% confidence interval [CI] [.909, .987]) and the presence of a substance use disorder (OR = 4.543; 95% CI [1.058, 19.499]) were the most robust predictors of attrition. Dropouts also were more likely to have a depressive disorder, more comorbid diagnoses, and more severe depression and suicidal symptoms. Conclusions Findings suggest that clinician‐assessed poorer overall functioning and a substance use disorder diagnosis are risk factors for attrition among suicidal individuals, above and beyond other symptom measures. Further research is warranted to investigate attrition in additional outpatient samples.