Morbidity and mortality remain high for patients with hypoplastic left heart syndrome during the interstage period between Norwood and Glenn despite ongoing QI efforts. We sought to identify associations between the site of interstage care, interstage events, and mortality. Data for patients enrolled in the National Pediatric Cardiology Quality Improvement Collaborative registry from July 2008 through February 2013 were reviewed. Patients had outpatient interstage care at (1) the surgical site (SS) performing Norwood, (2) a non-surgical site (NSS), or (3) a combination. Interstage events were compared among these groups and, when applicable, by distance from SS to NSS. 688 patients from 47 sites met entry criteria. Patients were followed at the SS 411 (60%), NSS 121 (17%), or a combination 143 (21%). Data were not available for 13 (2%). There were 66 deaths (10%) among the entire cohort: 37 (9%) at SS, 13 (11%) at NSS, 15 (10%) at a combination. The proportion of deaths among these groups was not statistically significant (p = 0.60), nor was there a difference based on SS-to-NSS distance. Patients followed at the SS were more likely to have problems detected with feeding (p = 0.03) and breathing (p = 0.002), and ED visits (p < 0.001). The site of interstage care was not associated with mortality, nor was there a difference based on SS-to-NSS distance. Patients followed at the SS had more detected breathing and feeding problems, and ED visits. Further study is required to elucidate the clinical significance of these differences.