Collaborative knowledge networks represent a core building block of regional innovation systems. They are constantly evolving, driven by a wide range of both endogenous and exogenous mechanisms. A number of empirical studies have signaled that interorganizational trust may be a key determinant of network tie formation, especially during periods of high uncertainty, yet findings remain inconclusive as a result of two limitations. On the one hand, most network studies adopt a static perspective, ignoring the evolution of the nodes and their ties over time, and on the other hand, sources of trust are typically conceptualized only on a dyad or node level. Hence, the aim of this study is, first, to establish the effect of different types of interorganizational trust – at the level of the node, the dyad and the network – on tie formation in regional R&D networks. Next, we explore to what extent do these types of interorganizational trust vary during periods of high uncertainty such as a global pandemic. We test our hypotheses in the context of the Valencian region focusing on the evolution of a policy-induced R&D network in the period 2018-2021.