. . . Keaton, S. A., & Honeycutt, J. M. (in press, 2014). The effects of team identity formation and sport team identification on mental health, cognition, behavior, and physiology. In J. M. Honeycutt, C. Sawyer, & S. A. Keaton (Eds.), The influence of communication in physiology and health. New York, NY: Peter Lang. Chapter 5 The Effects of Team Identity Formation and Sport Team Identification on Mental Health, Cognition, Behavior, and Physiology Shaughan A. Keaton and James M. Honeycutt Sport team fandom is a worldwide phenomenon. Whether baseball in New York, cricket in Australia, futebol in Brazil, fútbol americano in the US, hockey in Canada, basketball in China, or rugby in New Zealand, the outcomes of sporting contests affect those who invest their time, money, and self into sport teams. There are at least two important considerations when considering sport team fandom in these contexts. The first queries into the antecedents, or influences (i.e., input), of sport team fandom; the second speculates about what ways are we affected (i.e., output). These two process- es are central for explaining how people come to be fans of a team and how it affects them: These processes are called team identity formation (TIF) and sport team identification (STI; for more information, see Keaton & Gearhart, in press). STI is a psychological connection to a sport team and TIF consists