The work contributes to the debate on the theory of the firm. We focus our attention on three aspects: the role of the entrepreneur, the importance of co-ordination mechanisms within and outside the firm, the fact that the growth of the firm may be “governed” by stochastic processes. The emphasis on the entrepreneur is justified by the fact that the latter has been often “forgotten” by the theory. The attention to co-ordination is important in pointing out that firms are not islands closely organised inside and are not connected with other firms and consumers only by pure market relations; here we recall various analyses concerned with business groups. Finally, we refer to Gibrat’s Law as a possible explanation of firms’ growth processes, together with other explanations