The family business literature shows growing interest in inter-firm cooperation involving family firms (Roessl, 2005). This is due to the recognition that inter-firm cooperation enables firms to develop competitive advantage through enriched knowledge and access to crucial resources and new markets by cooperating with other firms. Particularly, efforts have been made by scholars to measure how family businesses compare with non-family businesses in different aspects of inter-firm cooperation. While some scholars conclude that family firms are less likely to engage in and less successful in inter-firm cooperation, other scholars find support for the opposite argument (Pittino and Visintin, 2011; Miller et al., 2009). In this article I reveal that this ongoing paradox in the literature is due to methodological challenges which make cogent understanding and grasp of inter-firm cooperation difficult in the family business context. First, I organize previous studies that used ‘family influence’ as a variable in inter-firm cooperation during the period 1982 -2012 based on the kind of inter-firm relationship studied and measures employed. Second, I synthesize the research findings into a model of inter-firm cooperation which provides a novel way of understanding the previous studies within their theoretical and empirical context. Third, I provide an interpretation of the literature based on the model to clarify the causes of the paradoxical findings and to show how previous studies provide complementary rather than contradictory conclusions. Fourth, I specify potential paths for future research.