Over the past decades, government agencies have faced various institutional pressures while engaging in interagency collaboration within a government organization. In particular, new public management (NPM) doctrines (e.g. performance measurement) have widely diffused across all levels of government in the U.S. and other countries, including South Korea. Meanwhile, the governance movement has emphasized the role of citizen participation in building and sustaining governance mechanisms. For example, in early 2000, the City of Seoul in South Korea adopted performance management practices such as performance-based promotion and performance-based budget as a means of reforming city management. At the same time, the City of Seoul has faced growing demands for citizen participation in policy decision making process and has adopted various online (e.g. online policy forums) and conventional citizen participation programs (e.g. citizen members of committees). Interagency collaboration can be viewed as a network strategy in response to institutional pressures. Recently, a few studies have examined the relationship between competing institutional pressures and organization’s network responses. Yet, they implicitly assumed that organizations face those pressures similarly, which limits our understanding about exactly how different forces shape agencies’ network formation. This research asserts that agencies cope with competing institutional pressures differently and thus, their responses, in terms of the forms of collaboration structures that emerge, varies depending on the nature and degree of pressures facing agencies. The purpose of this study is to better understand how agency managers perceive competing institutional pressures (e.g. performance management expectations and citizen participation demands) and how their different perceptions affect strategies for building interagency collaboration networks within an organization. For the analytical purpose, this research focuses on structural holes, which refer to network positions that connect otherwise disconnected agencies, as the main structural characteristic of interagency collaboration networks. Drawing the literature of NPM, citizen participation, and social networks (i.e., Burt’s structural holes and Coleman’s closed network), this research develops a theoretical model of collaboration structure and hypotheses. The hypotheses are tested using network and survey data collected 2009 from 134 agency managers. The survey response rate was 91.7 %. Preliminary results show that agencies under greater performance management pressure tend to locate themselves in collaboration networks rich in structural holes while agencies facing greater citizen participation demands tend to embed themselves to collaboration networks with fewer structural holes. In other words, performance-oriented management pressures drive city agencies to seek competitive structural positions within collaborative networks. Meanwhile, the norms of citizen participation lead agencies to build more closed collaborative networks. Based on findings, this research will discuss how performance-oriented management and citizen participation practices serve as facilitators or barriers for agencies to build such network strategies as interagency collaboration. Also, this research concludes by considering the managerial and policy implications for government agencies’ network strategies in response to competing institutional pressures.