At times of discontinuous technological change co-operation represents a viable strategy for both incumbents and new-entrants, provided that the choice of co-operation is consistent with the firm's business strategy (market-pull and generalist vs. technology-push and specialist) and with its degree of organizational and technological flexibility. A clear understanding of these two elements constitutes a necessary managerial pre-requisite for an effective co-operative strategy. Evidence from the UK fibre-optics industry suggests that managers can choose between two ideal types of co-operation. On the one hand, structured co-operation involves highly engineered partnerships at the inter-organizational level designed to gain control over, or access to, the commercialisation of the new technology for standard applications in the wider market; on the other hand, unstructured co-operation relies on informal relationships between individuals in separate organizations, with the intention of sustaining the development of innovative applications of the new technology for specialist market niches. Being a new-entrant or an incumbent does not necessarily explain the type of co-operation adopted - but there is evidence that market-pull, generalist strategies and lower levels of technological and organizational flexibility are associated with structured co-operation, whereas technology-push, specialist strategies and higher levels of flexibility combine with co-operative strategies of the unstructured type.