Brand extensions are increasingly implemented by sport organizations to create additional revenue streams and enhance brand strength. Although brand extensions have been a topic of extensive study in mainstream marketing (e.g., Aaker & Keller, 1990; Broniarczyk & Alba, 1994; Keller, 1998; Rangaswamy, Burke, & Oliva, 1993; Reddy, Holak, & Bhat, 1994), limited efforts to examine this practice in the sport setting have been undertaken (Chadwick & Clowes, 1998). Given the increasing prevalence of this marketing strategy for sport organizations, this study explores the factors that constitute a successful brand extension in the sport setting. A review of relevant literature is conducted, with a focus on motivations for extensions and identifying the keys to successful brand extensions. In order to examine the applicability of these findings to the team sport setting, descriptive research was conducted with the Marketing Managers of twelve U.S. professional teams. The findings of this research are consistent with common themes found in the marketing literature. However, there were unique factors associated with extensions in the sport setting. For example, beyond generating revenue, some extensions were introduced to enhance the emotional attachment between the consumer and the team. There were also unique variables contributing to the success of brand extensions introduced by professional sport teams, such as winning and the management of the extension.