ObjectivesHybrid stage I palliation has been used in many clinical scenarios including initial palliation in single ventricle heart disease, a bridge to biventricular repair, a bridge to transplant, and as a destination therapy. There is considerable hybrid stage I palliation practice variation, which we aimed to better understand in this study. MethodsSurvey-based assessment of practice variation related to hybrid stage I palliation was sent to congenital heart centers across the United States and Canada. ResultsOf the 106 centers surveyed, responses were received from 54 centers (50.9%). Of respondents, 45 centers perform hybrid stage I palliation. Centers most commonly (97.7%) perform hybrid stage I palliation on “high-risk” patients with single ventricle heart disease. Regarding the technical aspects of hybrid stage I palliation, most centers (95.3%) accomplish restrictive pulmonary blood flow using pulmonary artery bands and primarily use changes in oxygen saturation (34.1%) to identify appropriate restriction. Ductal stents are most often used (67.4%) to maintain ductal patency. Only 10 centers (23.3%) routinely enlarge the atrial septal defect. Indications for atrial septal defect intervention varied widely. Most centers (71.9%) discharge patients home to follow with a formal “interstage” program. ConclusionsThere is significant variation in practice patterns for hybrid stage I palliation indications, technical aspects, and postoperative care. Therefore, generalizability of single-center studies on outcomes after hybrid stage I palliation is limited. Future multicenter studies are needed to best delineate which patients benefit most from hybrid stage I palliation and to further define optimal approaches to caring for these patients.