Objective: The validity and clinical utility of the Reynolds Adolescent Depression Scale, Beck Hopelessness Scale, Suicidal Ideation Questionnaire-Junior, and Suicide Probability Scale (SPS) were examined longitudinally among suicidal adolescents. Method: Between 1998 and 2000, 289 psychiatrically hospitalized, suicidal youth, ages 12 to 17 years, participated in this study. Self-report measures were completed at baseline. Clinician-rated suicidality and suicide attempt were collected at baseline and 6-month follow-up. Results: Baseline self-reports were internally consistent and strongly intercorrelated within male, female, white, and black subsamples. All of the measures predicted follow-up suicidality and suicide attempts. Using published cutoff scores, the Beck Hopelessness Scale and SPS were moderately to highly sensitive predictors of subsequent suicide attempts, as was the Suicidal Ideation Questionnaire-Junior for predicting suicide attempts and broad suicidality. Alternative cutoff scores that predicted outcomes with moderate and high sensitivity also were examined, with attention to resultant sacrifices in specificity. Conclusions: Baseline self-report scores predicted follow-up suicidality. SPS contributed uniquely to prediction of future suicidality and suicide attempt. SPS may supplement other sources of information when assessing suicide risk with this population. (Contains 4 tables.)