An important recent development in the achievement goal literature is to define achievement goals strictly as aims. In this overview, we argue that this restrictive definition of achievement goals paves the way for a systematic consideration of the autonomous and controlled reasons underlying individuals' achievement goals, a distinction central to self-determination theory. To stimulate work in this area, we formulated five propositions, arguing that consideration of the "why" (i.e., type of reasons) in addition to the "what" (i.e., type of aims) of achievement goals (a) provides an account for the regulatory basis of achievement goals, (b) opens the door for other motivation theories to be linked to the achievement goal literature, (c) matters in terms of predicting outcomes, (d) allows for a richer account of contextual forces influencing motivation, and (e) sets the stage for an enriched hierarchical model of achievement motivation. In closing, we discuss various future research directions.