PURPOSE: Entrustable professional activities (EPAs) represent the routine and essential activities that physicians perform in practice. Although some level of supervision scales have been proposed, they have not been validated. In this study, the investigators created level of supervision scales for EPAs common to the pediatric subspecialties and then examined their validity in a study conducted by the Subspecialty Pediatrics Investigator Network (SPIN). METHOD: SPIN Steering Committee members used a modified Delphi process to develop unique scales for six of the seven common EPAs. The investigators sought validity evidence in a multisubspecialty study in which pediatric fellowship program directors and Clinical Competency Committees used the scales to evaluate fellows in fall 2014 and spring 2015. RESULTS: Separate scales for the six EPAs, each with five levels of progressive entrustment, were created. In both fall and spring, more than 300 fellows in each year of training from over 200 programs were assessed. In both periods and for each EPA, there was a progressive increase in entrustment levels, with second-year fellows rated higher than first-year fellows (P < .001) and third-year fellows rated higher than second-year fellows (P < .001). For each EPA, spring ratings were higher (P < .001) than those in the fall. Interrater reliability was high (Janson and Olsson's iota = 0.73). CONCLUSIONS: The supervision scales developed for these six common pediatric subspecialty EPAs demonstrated strong validity evidence for use in EPA-based assessment of pediatric fellows. They may also inform the development of scales in other specialties.