PurposeThis study examines 56 R&D projects, in each of which several organizations cooperate via an electronic system platform. The aim was to examine the relationships among leadership, cooperation, and project success (product improvements).Design/methodology/approachThe paper investigates to what degree the relative importance of different aspects of leadership and cooperation in R&D projects on electronic platforms differs depending upon situational conditions.FindingsGiven a low level of electronic system and process integration, the frequency of personal contacts makes a significant contribution to explaining success variance. The quality of communication (team trust) is particularly important in the case of a high degree of electronic linkage. Enhancement of team spirit is more conductive to success in larger groups. Ensuring frequent personal contacts and clarifying goals, tasks, and responsibilities, respectively, contributes significantly to explaining success variance in large projects (but not in small ones). In projects with a great degree of task novelty (exploration), trustful communication becomes particularly important.Research limitations/implicationsThe sample was rather small, as is the population of interorganizational cooperative projects that was studied. Further research is needed in regard to the moderator effects that is posited.Practical implicationsKnowing what is important in a particular project configuration makes it possible to take informed action with respect to the success criterion.Originality/valueThe paper shows how, in the context of R&D projects on electronic platforms, the relative importance of different aspects of leadership and cooperation depends on the specific project characteristics.