The creation of a coaching environment that fosters psychological need-satisfaction (Selfdetermination theory; Deci & Ryan, 1985) is proposed to facilitate positive psychological well-being for athletes. Previous studies have shown consistent support for Selfdetermination theory (SDT) with autonomy-supportive environments linked with adaptive outcomes, such as superior performance, enhanced self-worth, increased effort, and selfdetermined motivation; while controlling environments have been linked with increased attrition and extrinsic motivation or amotivation (e.g., Mageau & Vallerand, 2003;Mallett, 2005). In this way, much of the research in autonomy-supportive coaching has focused on the impact of coaching behaviours on athlete outcomes. Whilst this is an important focus of inquiry there has been a dearth of research examining those causal factors that impact coaches' behaviours in the first case. This thesis underscores the need for future research to examine the antecedents to coaching behaviours, which is central to understanding the complexity and challenges in promoting an autonomy-supportive approach to sport coaching (Amorose, 2007).Study one compared coaches' perceptions of their coaching with those of the players. Moreover, an alternative means of measuring athlete perceptions of their coaches' behaviours using a single item scale was examined. Data were collected from 55 elite youth basketball teams (coach-player dyads, including 55 coaches and 258 players) at a major basketball tournament. The findings suggested an incongruency between coaches and athletes in how they perceive the coaches' behaviour. The coaches in the sample reported their behaviours as higher in autonomy-support and lower in controlling characteristics compared to their athletes. These differing perceptions of coaching behaviours between coaches and athletes highlighted a fundamental discrepancy in how coaches and athletes view the provision of coaching. Second, the single item measure of autonomy-supportive coaching was empirically supported. This study highlighted that ii coaches and athletes perceived the coaching environment somewhat differently, namely through the perception of coaching behaviours.The key aim of study two was to develop an understanding of the contextual factors that influence the behavioural choices of coaches to adopt an autonomy-supportive interpersonal style and how athletes' perceived these behaviours in relation to their conceptions of quality coaching. Six male coaches, aged between 28 and 46 years were involved in this study. The second group of participants in this study were male, independent high school athletes (n = 29) from six schools. These athletes were coached by the six male coaches mentioned above and formed part of the Open age group basketball team for their school. The ages of the athletes ranged between 14 and 17 years and the total playing experience of the athletes averaged 5.75 years. Data were collected through one semi-structured interview with the coach and one focus gro...