Pain behaviors are important indicators of functioning in chronic pain; however, no self-reported pain behavior instrument has been developed for pediatric populations. The purpose of this study was to create a brief pediatric measure of patient-reported pain behaviors as part of the Patient-Reported Outcome Measurement Information System (PROMIS). A pool of 47 candidate items for this measure had been previously developed through qualitative research. In this study, youth with chronic pain associated with juvenile fibromyalgia, juvenile idiopathic arthritis, or sickle cell disease (ages 8-18 years) from 3 pediatric centers completed all 47 candidate items for development of the pain behavior item bank along with established measures of pain interference, depressive symptoms, fatigue, average pain intensity, and pain catastrophizing. Caregivers reported on sociodemographic information and health history. Psychometric properties of the pain behavior items were examined using an item response theory framework with confirmatory factor analysis and examination of differential item functioning, internal consistency, and test information curves. Results were used along with expert consensus and alignment with the adult PROMIS pain behavior items to arrive at an 8-item pediatric pain behavior short form, and all 47 items were retained in a calibrated item bank. Confirmatory factor analysis and correlations with validated measures of pain, pain interference, and psychosocial functioning provided support for the short form's reliability and validity. The new PROMIS pediatric pain behavior scale provides a reliable, precise, and valid measure for future research on pain behavior in school-aged children with chronic pain.