Purpose: The purpose of this research is to focus on the role of trust in knowledge sharing. Social capital researchers have put forward trust as an important force behind the sharing of knowledge. This study aims to investigate whether trust indeed explains knowledge sharing relationships, or whether there are in fact much more important drivers of the sharing of knowledge in new product development projects. Design/methodology/approach: A survey study was carried out in large new product development projects, including 23 teams and 91 individuals. Findings: The main finding is that trust is a poor explanatory of knowledge sharing. Team membership, on the other hand, has the largest effect on the density of knowledge sharing relationships. Social capital thus does not reside in trust but in team membership, especially for longer-lived teams. Research limitations/implications: There should be more attention for other aspects affecting knowledge sharing, including team characteristics. Originality/value: This article will be of use to organizations conducting new product development, wishing to manage knowledge sharing as social capital. Moreover, this article provides more insight on the value of the trust in knowledge sharing and offers directions for future theory development.