Recent capital market research evidence suggests that a large proportion of public companies worldwide are characterized by controlling stockholders who are more often families, usually the founder(s) or their descendants. There has been considerable debate on whether “family” firms can indeed be accurately delineated from nonfamily firms given the diversity and abundance of family business definitions in the literature. This paper provides a robust definition of family business for the purposes of capital market research. Using an accounting-based definition of family business, the paper outlines a four-step procedure that provides validation for identifying family controlled companies listed on the Australian Stock Exchange. A significant feature of the research methodology was reliance on data collected from the Australian Securities and Investments Commission. Having access to the corporate regulator's restricted data enabled the researchers to establish important links between directors and their private related entities.