Chronic postsurgical pain is defined as pain that develops or intensifies following a surgical procedure. After major surgery, around 20% of children and adolescents develop chronic postsurgical pain, and, as part of it, negative consequences on their quality of life. Emotion-related factors such as the variability of emotions, how emotions are regulated, and how well someone is able to differentiate between different emotions have in part been studied in other types of chronic pain. To date, no study examined emotion-related factors in the development and maintenance of chronic postsurgical pain. This observational study includes five assessment time points, one before and four after major surgery, with the goal to identify emotion-related factors that increase or decrease the risk for the development of chronic postsurgical pain.