This paper investigates the effects of separation of ownership and control due to vote differentiation on listed family firms’ investment performance. We study both the question whether family controlled firms have better investment performance than non-family firms and as to whether this investment performance is negatively affected by a separation of ownership and control due to vote differentiation. Marginal q is used as a performance measure. The empirical analysis shows that family control has a positive impact on investment performance when ownership and control are aligned while separation of ownership and control in terms of vote-differentiated shares lowers investment performance.