Research Questions 1. How can compound network structures influence the effectiveness of network governance mechanisms in a Bto-B electronic marketplace? 2. How can a market maker control different network flows (e.g. information, cash and material) in a B-to-B electronic marketplace to motivate participant firms to comply with different network governance mechanisms? Summary of Findings This paper explores the nature of compound networks in a B2B electronic market (EM) context and builds a conceptual model of how different network structures may influence network governance mechanisms. The model has the following propositions. Community building (e.g. online forums) is more effective in high-density cooperative networks, less effective in high-density competitive networks, centralized cooperative networks and networks with more cliques. For reputation mechanisms, negative gossip (e.g. thumbs down buttons) is more effective to reveal real interfirm interactions in high-density cooperative networks, while positive gossip (e.g. like buttons) is more effective in high-density competitive networks. Tertius gaudens (e.g. product ranking) is less effective in high-density cooperative networks, and more effective in high-density competitive networks and centralized cooperative networks. However, tertius iugens (e.g. suggesting suppliers) is more effective in high-density cooperative networks and highly diverse networks, less effective in high-density competitive networks. Two-step leverage (e.g. boycotting) is more effective in centralized cooperative networks. Social psychological mechanisms including trust, reciprocity, power imbalance, group norms influence the relationships between network structures and governance. A market maker also needs to control different material and immaterial network flows (e.g. cash, material and information) to influence participant firms' motivations to comply with the governance mechanisms. Key Contributions 1. This study is the first study to bring the network governance concept into the context of B2B EMs, which provides a novel angle to study the effectiveness of platform governance. It also applies a structural and networklevel view to study coopetition or compound relationships in B2B marketing in an online context. This structural view leads to a contingent theory of network governance effectiveness. 2. This study advances the understanding of social network theory in a B2B electronic market (EM) context. It proposes an innovative application of combining two competing streams in social network theory (structuralist and connectionist approaches) to tackle the main limitations in network governance literature, which contributes to ongoing debates about agency and structure in the network literature. 3. For managerial implications, the findings will help market makers decide on how to adopt the right network governance mechanisms to manage conflicts and opportunistic behaviours. The findings will also lead to better platform design for maximizing the effectiveness of governance mechanisms by controlling different flows (e.g. cash, information, materials). [ABSTRACT FROM AUTHOR]