Collaborative quality improvement and learning networks have amended healthcare quality and value across specialities. Motivated by these successes, the Pediatric Acute Care Cardiology Collaborative (PAC3) was founded in late 2014 with an emphasis on improving outcomes of paediatric cardiology patients within cardiac acute care units; acute care encompasses all hospital-based inpatient non-intensive care. PAC3 aims to deliver higher quality and greater value care by facilitating the sharing of ideas and building alignment among its member institutions. These aims are intentionally aligned with the work of other national clinical collaborations, registries, and parent advocacy organisations. The mission and early work of PAC3 is exemplified by the formal partnership with the Pediatric Cardiac Critical Care Consortium (PC4), as well as the creation of a clinical registry, which links with the PC4 registry to track practices and outcomes across the entire inpatient encounter from admission to discharge. Capturing the full inpatient experience allows detection of outcome differences related to variation in care delivered outside the cardiac ICU and development of benchmarks for cardiac acute care. We aspire to improve patient outcomes such as morbidity, hospital length of stay, and re-admission rates, while working to advance patient and family satisfaction. We will use quality improvement methodologies consistent with the Model for Improvement to achieve these aims. Membership currently includes 36 centres across North America, out of which 26 are also members of PC4. In this report, we describe the development of PAC3, including the philosophical, organisational, and infrastructural elements that will enable a paediatric acute care cardiology learning network.