Introduction: TREKK is a national knowledge mobilization network of clinicians, researchers and parents aimed at improving emergency care for children by increasing collaborations between general and pediatric emergency departments (ED). This study aimed to determine patterns of knowledge sharing within the network and identify connections, barriers and opportunities to obtaining pediatric information and training. Methods: Social network analysis (SNA) uses network theory to understand patterns of interaction. Two SNAs were conducted in 2014 and 2015 using an online network survey distributed to 37 general EDs. Data was analyzed using UCI Net and Netdraw to identify connections, knowledge sharing and knowledge brokers within the network. Building on these results, we then conducted 22 semi-structured follow-up interviews (2016) with healthcare professionals (HCPs) at General EDs across Canada, purposefully sampled to include individuals from connected and disconnected sites, as identified in the SNA. Interviews were analyzed by 2 reviewers using content and thematic analysis. Results: SNA data was analyzed for 135 participants across the network. Results from 2014 showed that the network was divided along provincial lines, with most individuals connecting with colleagues within their own institution. Results from 2015 showed more inter-site interconnectivity and a reduction in isolated sites over time from 17 to 3. Interview participants included physicians (59%) and nurses (41%) from 18 general EDs in urban (68%) and rural/remote (32%) Canada. HCPs sought information both formally and informally, by using guidelines, talking to colleagues, and attending pediatric related training sessions. Network structure and processes were felt to increase connections, support practice change, and promote standards of care. Participants identified personal, organizational and system-level barriers to information and skill acquisition, including resources and personal costs, geography, dissemination, and time. Providing easy access to information at the point of care was promoted through enhancing content visibility and by embedding resources into local systems. There remains a need to share successful methods of local dissemination and implementation across the network, and to leverage local professional champions such as clinical nurse liaisons. Conclusion: This study highlights the power of a network to increase connections between HCPs working in general and pediatric EDs. Findings reinforce the critical role of ongoing network evaluation to improve the design and delivery of knowledge mobilization initiatives.