Given that a strong owner has been identified as an important factor in the success of megaprojects, there has been a growing recognition of the importance of megaproject owner organizational capabilities. However, the questions of what organizational capabilities do owners need to foster successful megaprojects, and whether these capabilities are the stronger the better, have yet to be addressed. To answer these questions, this study identified the dimensions of owner organizational capabilities based on literature and interviews, and developed several sets of parallel hypotheses. Based on the 229 valid questionnaire data collected, the relationships between owner organizational capabilities and megaproject success were analyzed through hierarchical multiple regression, and the results were discussed through expert interviews. The findings show that owner coordination, dynamic, and system integration capabilities have positive impacts on megaproject success, with coordination capabilities being the most significant. While the impact of motivational capabilities on megaproject success is inverted U-shaped. This study provides an actionable dimensional framework for megaproject owner capabilities, moving the field of owner organizational capabilities beyond the conceptual level. This study provides empirical evidence for the importance of megaproject owner organizational capabilities and takes a more dialectical view of a strong owner. The empirical results can provide insights and guidance on the configuration and development of megaproject owner capabilities.

External program manager involvement can provide professional and systematic management services to owners. It can help to manage and coordinate different subprojects and ensure the achievement of the overall strategic goals of large projects. The promotion of external program manager involvement is not only efficiency-driven, but the institutional environment also has a significant impact. This study developed a theoretical model to explain how external program manager involvement is influenced by external institutional forces (coercive, mimetic, and normative pressures) and internal top management support. Based on a questionnaire survey, this study tested the research model through partial least-squares structural equation modeling. The empirical results revealed that coercive pressures have no significant impact on external program manager involvement; owners' top management support acts as a complete mediator between the mimetic pressures and external program manager involvement; normative pressures have the greatest impact on top management support and external program manager involvement, and top management support plays a key but partially mediating role. A direct contribution of this study is to reveal how different types of isomorphic pressures can be better exercised to facilitate the involvement of external program managers. Going further, by incorporating both external institutional pressures and internal top management support into the research model, this study provides insight into how organizations are influenced by external institutions to apply tools or approaches internally.