Through electronic health record implementation, national healthcare systems are aiming for care integration and enhancement. However, the path to large-scale electronic health record implementation is seldom smooth, involving multiple stakeholders with diverse interests and influences. This study proposes a framework that draws on both stakeholder and institutional theories to understand the complex dynamics of stakeholder interactions and institutional pressures over time during electronic health record systems implementation. This framework is utilized to analyze the national electronic health record programs of Singapore and England, which provide contrasting perspectives on how two top-down system implementations took place with different outcomes. Our results suggest that in the Singapore case, the presence of boundary spanners, supporting implementation agency that included IT staff from healthcare organizations, and greater engagement with medical professionals were associated with more positive dynamics of stakeholder interactions (e.g. limited pushback from professionals or the press) during electronic health record implementation than in England. Differences in the healthcare structures and systems, electronic health record project organization, and the combined influences of institutional pressures shed light on the varying implementation paths and outcomes in the two cases. This study adds to the health information technology literature through a comparative examination of the organizational and social processes during complex national healthcare integration projects. It also contributes to the institutional and stakeholder literatures in several ways, in particular by depicting the processes and outcomes of the dynamics of isomorphic pressures played out under different institutional conditions. Finally, our proposed framework provides a useful conceptual tool for analyzing such complex IT implementations across multiple stakeholders.