The purpose of this study was to develop a brief, self-report instrument that would assess the most important known risk factors for suicide and to validate it against a diagnostic profile of suicide risk obtained through a well-validated structure interview. Other goals were to measure test-retest reliability and to compare the Columbia SuicideScreen (CSS) with the Beck Depression Inventory (BDI), a widely used depression screening instrument. Over 1,700 students in 9th to 12th grade completed the CSS and BDI during school hours in 1991 to 1994. Three hundred fifty-six students that screened positively and 285, group matched on age, gender, and ethnicity, that screened negatively were examined on the Diagnostic Interview Schedule for Children (DISC) to assess validity. The DISC-based suicide risk criterion was suicidal ideation or prior suicide attempt and a DSM-III-R diagnosis of major depression or dysthymia or substance use. Test-retest reliability was assessed in a subsample of 85. The results showed that the algorithm that afforded the best balance against the validity criterion was suicidal ideation or previous attempt and an intermediate or higher score on the scales for unhappy or withdrawal or irritability and anxiety. The CSS had the potential for having high (0.88) sensitivity at the expense of specificity. Sensitivity remained high but was somewhat reduced (0.75) when the algorithm having the best balance with specificity (0.83) was used. The CSS demonstrated good sensitivity and reasonable specificity identifying students at risk for suicide. A second-stage evaluation would be needed to reduce the burden of low specificity. 4 tables, 40 references