Governance of family firms differs from mainstream corporate governance in an important respect: Important owners, i.e., family members, may have multiple roles in the business. In this paper, we develop and test a model of family firm governance that incorporates both formal control and social control aspects of governance. Governance based on the formal control draws on agency theory, whereas the social control aspects draw on social theories of governance, addressing social capital embedded in relationships. Drawing on these theories, we examine the influence of different governance mechanisms on the quality of strategic decision making. The Family Business Governance Model is tested using survey data from 192 family firms in Finland. We use structural equation modeling in testing the empirical validity of the model. The empirical analysis largely supports our hypotheses on formal control and social control as well as their influences on the decision- making quality.