Inadequate pain assessment is a barrier to appropriate pain management, but single-item “pain screening” provides limited information about chronic pain. Multidimensional pain measures such as the Brief Pain Inventory (BPI) are widely used in pain specialty and research settings, but are impractical for primary care. A brief and straightforward multidimensional pain measure could potentially improve initial assessment and follow-up of chronic pain in primary care. To develop an ultra-brief pain measure derived from the BPI. Development of a shortened three-item pain measure and initial assessment of its reliability, validity, and responsiveness. We used data from 1) a longitudinal study of 500 primary care patients with chronic pain and 2) a cross-sectional study of 646 veterans recruited from ambulatory care. Selected items assess average pain intensity (P), interference with enjoyment of life (E), and interference with general activity (G). Reliability of the three-item scale (PEG) was α = 0.73 and 0.89 in the two study samples. Overall, construct validity of the PEG was good for various pain-specific measures (r = 0.60–0.89 in Study 1 and r = 0.77–0.95 in Study 2), and comparable to that of the BPI. The PEG was sensitive to change and differentiated between patients with and without pain improvement at 6 months. We provide strong initial evidence for reliability, construct validity, and responsiveness of the PEG among primary care and other ambulatory clinic patients. The PEG may be a practical and useful tool to improve assessment and monitoring of chronic pain in primary care.