PurposeThe purpose of this paper is to examine the practices and processes of trust building and use in collaborative networking for product innovation and to compare face to face with virtual networking.Design/methodology/approachGuided by a literature review and preliminary participant observation, 16 open ended interviews collected data about the processes in 11 small biotech firms. These data were inductively analysed by the constant comparative method to develop explanatory themes.FindingsTrust was seen as a requirement for successful collaborative innovation, but the paper identified how different dimensions of trust are located in the trust building processes. Trust works by creating a platform of confidence that fosters flows of information and the exchange of tacit knowledge. Two types of trust relationships, the technical and the social, work in different ways to produce different, but complementary, types of trust. Virtual environments suit technical trust building but are less suited to developing deeper, more enduring forms of trust.Research limitations/implicationsThese different approaches to collaboration are often implicit. But if practitioners are made aware of how they work, they can use the most appropriate approach to build trust.Practical implicationsThe method and sample restrict general application, but the explanatory framework may be conceptually generalisable.Social implicationsNetworking for innovation is seen as much social as technical.Originality/valueThe paper contributes conceptually by theorising the trust building process and its role in knowledge sharing and collaborative innovation. It addresses a gap in the literature in identifying how trust is produced, developed and employed in furthering innovation, in particular the behavioural patterns of using virtual networks in furthering innovation.