Validate the Ask Suicide-Screening Questions (ASQ) with youth in outpatient specialty and primary care clinics. This is a cross sectional instrument validation study assessing the validity of the ASQ with respect to the standard criterion, Suicidal Ideation Questionnaire (SIQ/SIQ Jr.). The sample included 515 English speaking youth ages 10–21 years old from outpatient specialty and primary care clinics. ASQ sensitivity, specificity, positive and negative predictive values (PPV/NPV), positive and negative likelihood ratios, c statistic and respective receiver operating characteristic curves were assessed. A total of 335 outpatient specialty and 180 primary care clinic participants completed the study. In outpatient specialty clinics, the ASQ showed a sensitivity of 100.0% (95% CI: 80.5–100.0%), specificity of 91.2% (95% CI: 87.5–94.1%), and NPV of 100.0% (95% CI: 98.7–100.0). In the primary care clinic, the ASQ showed a sensitivity of 100.0% (95% CI: 59.0–100.0%), specificity of 87.9% (95% CI: 82.0–92.3%), and NPV of 100.0% (95% CI: 97.7–100.0). Forty-five (13.4%) outpatient specialty clinic participants and 28 (15.6%) primary care clinic participants screened positive for suicide risk on the ASQ. The ASQ is a valid screening tool for identifying youth at elevated suicide risk in outpatient clinical settings. [ABSTRACT FROM AUTHOR]