Theoretical models of expectancy processes (e.g., Olson, Roese, & Zanna, 1996) have conceptualised the sources of information by which expectancies of others are formed, and suggest that expectancies have the potential to influence the cognitive, affective, and behavioural responses of both perceivers and targets. The main aim of this thesis was to examine expectancy effects within the coach-athlete relationship from the perspective of the athlete. Specifically, the aims were to examine: a) the sources of information that athletes deem influential when developing expectancies of a coach; b) the cognitive consequences of athletes' expectancies of coaches; c) the affective responses of athletes to initial expectancies of a coach; and d) the behavioural consequences of athletes' expectancies of their coach. In order to achieve these aims, the investigation employed a range of experimental methods including an explorative survey (study one); experimental designs, which involved obtaining athletes' ratings in response to a range of stimuli such as static photographs, written information, and dynamic video footage (studies two and three); and a field-based examination, which was assessed via a combination of notational analysis and questionnaire (study four). The main findings reveal that while static cues (e.g., gender) are deemed relatively unimportant during impression formation, dynamic cues (e.g., facial expressions) and third-party reports (e.g., reputation) are viewed by athletes as influential factors in the formation of expectancies about coaches. Specifically, the findings suggest that athletes' initial expectancies of an unknown coach's competency are influenced by the presentation of reputation information. Although the results show that coach gender also has a significant impact on athletes' expectancies, the effect of gender on athletes' expectancies was not as large as that of reputation information. In addition, reputation information is shown to significantly impact on athletes' positive affective responses to a coach. Finally, the results demonstrate that coach reputation impacts on athletes' attention, effort, and persistence during a training session. Overall, the research presented in this thesis provides support for the use of Olson et al.'s (1996) model of expectancy processes as a theoretical framework for the investigation of expectancy effects within the coach-athlete relationship. The thesis provides initial empirical support for the contention that athletes' expectancies of coaches impact on athletes' cognitive, affective, and behavioural responses. Such findings have important implications for coaching guidelines and the development of effective coach-athlete relationships. The proposal that third-party reports represent an influential source of information with regard to expectancy formation in sport has also received initial support.