Combining both interview data and empirical analyses at the patent and firm levels, we explore thevalue-appropriation and value-creation implications of R&D collaboration resulting in the co-ownershipof intellectual property (i.e. co-patents). We make an explicit distinction between three different typesof co-patenting partners: intra-industry partners, inter-industry partners, and universities. Our findingsindicate that the value-appropriation challenges of IP sharing are clearly evident with intra-industry co-patenting, where partners are more likely to encounter overlapping exploitation domains. Co-patentingwith universities is associated with higher market value, since appropriation challenges are unlikelyto play a role and collaboration may signal novel technological opportunities. Although we find someevidence that co-patenting corresponds to higher (patent) value, patents co-owned with firms aresignificantly less likely to receive self-citations, indicating constraints on the future exploitation anddevelopment of co-owned technologies.