The understanding of family businesses from the family side is still in its infancy. This is especially true in relation to how family members manage their relationships with one another and with the firm. Family growth and evolution are usually accompanied by a reduction in shared family meaning and purpose and greater divergence in the form of factional interests and intentions that harm the family and the firm. To counterbalance this negative impact, scholars generally advocate a set of corporate governance practices. However, few papers have analysed how family regulatory frameworks and family governance institutions affect family firm performance. To the best of our knowledge, no paper has analysed the complementary role of family rules and family governance institutions or their relationship with business performance. To fill this gap, we examine how family rules and family governance institutions affect firm performance. Drawing upon the concept of fit from organisation design, this paper shows the complementary role of family rules and family institutions, as well as the need for fit with family complexity. Analysis of a sample of family businesses shows that when family governance fits with family complexity, the relationship with firm performance is positive; any misfit leads to negative consequences