BACKGROUND: With increasing emphasis on integrat- ing behavioral health services, primary care providers play an important role in managing patients with suicidal thoughts. OBJECTIVE: To evaluate whether Patient Health Questionnaire-9 (PHQ-9) Item 9 scores are associated with patient characteristics, management, and depres- sion outcomes in a primary care-based mental health program. DESIGN: Observational analysis of data collected from a patient registry. PARTICIPANTS: Eleven thousand fifteen adults en- rolled in the Mental Health Integration Program (MHIP). INTERVENTIONS: MHIP provides integrated mental health services for safety-net populations in over 100 community health centers across Washington State. Key elements of the team-based model include: a disease registry; integrated care management; and organized psychiatric case review. MAIN MEASURES: The independent variable, suicidal ideation (SI), was assessed by PHQ-9 Item 9. Depres- sion severity was assessed with the PHQ-8. Outcomes included four indicators of depression treatment pro- cess (care manager contact, psychiatric case review, psychotropic medications, and specialty mental health referral), and two indicators of depression outcomes (50 % reduction in PHQ-9 score and PHQ-9 score < 10). KEY RESULTS: SI was common (45.2 %) at baseline, with significantly higher rates among men and patients with greater psychopathology. Few patients with SI (5.4 %) lacked substantial current depressive symp- toms. After adjusting for age, gender, and severity of psychopathology, patients with SI received follow-up earlier (care manager contact HR = 1.05, p < 0.001; psy- chiatric review HR = 1.02, p < 0.05), and were more likely to receive psychotropic medications (OR = 1.11, p = 0.001) and specialty referral (OR=1.23, p<0.001), yet were less likely to achieve a PHQ-9 score<10 (HR=0.87, p < 0.001). CONCLUSIONS: Suicidal thoughts are common among safety-net patients referred by primary care providers for behavioral health care. Scores on Item 9 of the PHQ- Received March 5, 2012 Revised June 5, 2012 Accepted July 31, 2012 9 are easily obtainable in primary care, may help providers initiate conversations about suicidality, and serve as useful markers of psychiatric complexity and treatment-resistance. Patients with positive scores should receive timely and comprehensive psychiatric evaluation and follow-up.