No validated measure for pain self-efficacy in children and adolescents is currently available in the German language, and existing English versions have limitations. This study used a thorough development process to create the Scale for Pain Self-Efficacy (SPaSE) in both German and English languages. Scale development was based on self-efficacy theory, adapting items from existing self-efficacy measures, and review of patients' perspectives. The final version of the 11-item SPaSE was created with expert discussions and testing of content validity, comprehensibility and construct validity. The validation process consisted of exploratory factor analysis, testing of item characteristics, internal consistency and sensitivity to change in two German samples of children and adolescents with chronic pain (study 1: outpatient sample N=150, inpatient sample N=31). Cross-validation in a US sample (study 2: N=98) confirmed the one-factor structure, the sound psychometric properties and reliability of the SPaSE. Sum scores of the SPaSE were negatively correlated with pain-related disability, pain intensity, passive pain coping strategies and emotional distress, in line with previous research. The valid and reliable SPaSE can be used in clinical practice to monitor pain treatment progress, advances the field of pain self-efficacy research in Germany, and opens the door to comparative research in German and English samples.