The influence of ownership structures on business performance has been researched extensively in the theoretical and empirical literature. The relevant literature suggests that ownership structure is one of the main corporate governance mechanisms influencing the scope of a firm's agency cost. Identifying differences between family firms and non-family firms and understanding the medium and long-term consequences of the family firms' strategic behaviour constitute two of the basic fields of family business research. This chapter focuses on the significant differences between family firms and non-family firms in general and determines if there are significant differences or analogies in these two different countries. It analyses the theoretical background concerning the family firms and non-family firms. The chapter outlines the research method and presents the sample analysed. The Italian family firms' results confirm the literature that emphasizes that firms with concentrated ownership structure, such as founding families, show lower profitability than firms with a dispersed ownership structure.