Research summary: Previous studies have emphasized firm and industry effects on variation in firm performance, but the relationship between forms of ownership and firm performance has been the focus of limited research. This article examines the extent to which ownership form (i.e., public or private ownership) and ownership structure (including diffused ownership and blockholding) affect firm performance. The results of an analysis of 30,525 European Union (EU) firms indicate that form of ownership is an important explanatory factor in the difference in performance among firms. These results underscore the need to study firms characterized by different ownership arrangements and to provide empirical evidence for the study of firm ownership in strategic management. Managerial summary: Motivated by growing evidence on the involvement of different types of owners in the strategies of firms, we studied the extent to which a firm's ownership form (type of legal incorporation, such as public and private ownership forms) and ownership structure (diffused ownership and blockholding) affect its performance. Our study of more than 30,000 firms from the European Union shows that ownership form differences explain some of the performance differences between firms. Our results also indicate that firms with different ownership forms are differently affected by their competitive environment. Overall, the study suggests that choosing the right ownership form can have important strategic consequences. Copyright © 2017 John Wiley & Sons, Ltd.