There are hypothesized associations between high training volume in youth sport and negative psychological and behavioural outcomes such as decreased enjoyment, burnout, and attrition. Autonomy support, however, is associated with positive motivational and behavioural outcomes. The purpose of this study was to concurrently explore the relationships of training volume and perceived coach autonomy support with enjoyment, commitment, burnout, and intentions to continue swimming in two very different competitive swimming contexts: summer club, with a brief season and time for sampling other sports, and winter club, requiring substantial near year-round investments of time and effort in swimming. Survey data were collected from 265 Canadian swimmers (Mage = 13.78), 40% from summer clubs, and 60% from winter clubs. Their parents provided training volume data. Correlations and path analyses revealed differences in the relationships between certain variables for summer versus winter swimmers. For example, autonomy support was not significantly related to obligatory commitment in the summer sample, but for winter swimmers, there was a medium negative association. Training volume was positively associated with functional commitment and intentions to continue swimming in winter swimmers, but not in summer swimmers. Differences between the two groups will be discussed in relation to their unique competitive contexts. Our findings suggest that some theories and models of motivation, sport commitment, and youth sport participation may not be generalizable across all youth sport contexts. Researchers should take care to fully describe the sport context under study when discussing any potential theoretical implications stemming from their findings.