The present study evaluated the factor structure, reliability, and validity of the Positive and Negative Suicide Ideation (PANSI; Osman, Gutierrez, Kopper, Barrios, & Chiros, 1998) inventory in a sample of high-school youths. The PANSI is designed as a measure of risk and protective factors related to suicidal behavior. Participants (114 boys and 103 girls) completed the PANSI and other self-report instruments. Results of the confirmatory factor analyses supported adequate fit of the 2-factor oblique model to the sample data. Both factor scales attained adequate levels of reliability. Boys and girls did not differ in their responses to the PANSI scales. The PANSI scale scores were associated with scores from related measures. Logistic-regression analyses were used to evaluate the contributions of the PANSI scale scores to differentiate between the study groups. Receiver Operating Characteristic (ROC) analyses, using data from the psychiatric suicide risk and high-school control youths, were used to identify cutoff scores of 1.63 and 3.33 for the PANSI-negative and PANSI-positive scales, respectively. © 2003 Wiley Periodicals, Inc. J Clin Psychol 59: 493–512, 2003.