The aim of this chapter is to explain how different trust-building mechanisms induce competitors to enter into two types of collaborative relationships: dyads and networks. We found that to start both dyadic and network coopetition, different trust-building mechanisms are needed. Notably, calculative trust is the most important mechanism for the introduction of dyadic coopetition, and third-party legitimation is crucial in network coopetition. We also found that trust-building is a challenging process, wherein dyadic coopetition involves only one partner, while multiple partners are involved in network coopetition. Therefore, it is easier to form coopetition dyads as compared to networks. Our research also shows that in small communities, trust based on reputation is important for long-term coopetition.