Sources of Heterogeneity in Family Firms: An Introduction Jess H. Chua James J. Chrisman Lloyd P. Steier Sabine B. Rau Family business researchers have devoted substantial attention to comparing family firms with nonfamily firms. Many of these comparisons rely on dichotomous variables, which implicitly treat family firms as homogeneous entities. However, recent studies have started to use moderators and mediators as well as continuous measures of family involvement in recognition of the heterogeneity of family firms. The articles and commentaries in this special issue contribute to a better understanding of that heterogeneity by examining how vision and goals, as well as the discretion engendered by family control, influence the innovation, internationalization, succession, professionalization, and proactive stakeholder engagement of family enterprises. Introduction This article introduces the ninth special issue in the ongoing series on “Theories of Family Enterprise” published in Entrepreneurship Theory and Practice. The purpose of the series is to provide a forum for studies that enhance theory and, thereby, increase our knowledge about family firms. Throughout the years, the articles and commentaries contained in the series have represented diverse viewpoints, directions, and topics. We, in turn, have attempted to add value by placing them within a larger context according to their contributions to the development of family business studies (Chrisman, Chua, & Steier, 2011; Eddleston, Chrisman, Steier, & Chua, 2010). This issue is no exception. When examining the articles and commentaries, we were struck with the realization that the focus of each seemed more about variations among family firms than about how family firms differ from nonfamily firms. Indeed, the heterogeneity of family firms has long been recognized (Melin & Nordqvist, 2007; Sharma, Chrisman, & Chua, 1997) but, until recently, the focus of research has been largely about the distinctions between family and nonfamily firms. Although both areas are important, there is evidence that the variations in the behavior and performance among family firms may be as large as, if not Please send correspondence to: Jess H. Chua, tel.: (403) 220-6331; e-mail: chua@ucalgary.ca, to James J. Chrisman at JChrisman@cobilan.msstate.edu, to Lloyd P. Steier at lloyd.steier@ualberta.ca, and to Sabine B. Rau at sabine.rau@whu.edu. P T E & 1042-2587 © 2012 Baylor University 1103 November, 2012 DOI: 10.1111/j.1540-6520.2012.00540.x