The present research sought to integrate self-determination theory and the achievement goal approach to achievement motivation by examining achievement goals as mediators of the link between psychological need support and both intrinsic and external motivation. We found support for our proposed integration, as mastery-approach and performance-approach goals were documented as partial mediators of the links between autonomy and competence need support, on the one hand, and intrinsic and external motivation, on the other. Statistical evidence was not obtained for the mediational role of performance-avoidance goals. The findings are discussed in terms of the ways in which they enrich both the self-determination and achievement goal frameworks.