This paper investigates the differences in behaviour and performance between family and non-family owned Spanish firms listed on the stock market. The general hypothesis of this paper is that strong preferences to maintain control of the company within the family restrict the decision for the maximisation of profits of family companies so that, in competitive markets, the economic viability of the family firm is conditioned to reach a higher level of productive efficiency than the non-family firm. The empirical evidence in the Spanish case shows that family firms operate under a restriction of size and produce more efficiently but, finally, obtain similar economic profits to non-family firms.

Key words: Family Ownership of Firms, Total Factor Productivity, Return on Investment.
JEL classification: G30, G32, G35.