2017 © Association for Applied Sport PsychologyThis study explored whether implicit beliefs and 2 × 2 achievement goals were related to enjoyment in youth sport over 1 year and whether perceived changes in the coach¿athlete relationship moderated these relationships. Indirect and conditional indirect effect analyses were conducted in a sample of 247 regular sport participants (Mage = 13.03 years). After adjusting for enjoyment at Time 1, incremental beliefs were indirectly related to Time 2 enjoyment via mastery-approach goals. However, this effect was evident only when the coach¿athlete relationship was perceived to have deteriorated. Results highlight the protective value of adaptive implicit beliefs and achievement goals in youth sport.