The paper provides the results of an empirical study of the informal relationships employed in the development of 35 successful technological innovations. Through the adoption of a network perspective, the multiple sources and pluralistic patterns of collaboration and communication in the innovation process were systematically explored. A variety of formal and informal boundary-spanning relationships were found to have been mobilised by the innovating organisations during the respective developments investigated. A typology of three boundary-spanning link-types between these internal and external networks was identified: liaisons, bridges, and link-pins. Particular individuals were highlighted as being important in maintaining these often strategic links. Indeed, these links were found to be the property of individuals rather than the organisational positions that they occupied.