Objective: The National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) was established in 2008 to improve outcomes of hypoplastic left heart syndrome (HLHS) during the interstage period. They evaluated changes in patient variables and practice variation between early and late eras. Design: Data including demographic, operative, discharge, and follow-up variables from the first 100 patients (6/2008–1/2010) representing 18 centers were compared with the most recent 100 patients (1/2014–11/2014) from these same centers. Results: Prenatal diagnosis increased from 69% to 82% (P =.05). There were no differences in gestational age or weight at Norwood. A composite of any preoperative risk factor occurred more frequently in the early era (59% vs. 34%, P <.01). While mean age at Norwood was similar (8.3 vs. 6.6 days, P =.2), the standard deviation was significantly lower in the recent era (10.4–6.4 days, P =.04). Use of RV-PA conduit increased (67%–84%, P <.01). Rates of complete discharge communication with both the primary care physician (31%–97%, P <.01) and primary cardiologist (44%–97%, P <.01) increased substantially. There were limited changes in feeding strategies. Use of home monitoring program increased (76%–99%, P <.01) with all participants in the late era monitoring both oxygen saturation and weight. Conclusions: Among NPC-QIC centers contributing patients to both eras, there were significant changes in preoperative risk factors, surgical strategy, discharge communication, and interstage care. Further study is required to determine an association between these changes and decreased mortality.