Two motivational theories - the Achievement Goal Theory and Self-Determination Theory - have recently been combined to explain students' motivation, making it possible to study the "what" and the "why" of learners' achievement strivings. The present study built on this approach by (a) investigating whether the distinction between autonomous or volitional and controlling or pressuring reasons can be meaningfully applied to the adoption of mastery-avoidance goals, (b) investigating the concurrent and prospective relations between mastery-avoidance goals and their underlying reasons and learning strategies when mastery-approach goals and their underlying reasons were also considered, and by (c) incorporating psychological need experiences as an explanatory variable in the relation between achievement motives (i.e., the motive to succeed and motive to avoid failure) and both mastery goals and their underlying reasons. In two Turkish university students samples (N = 226, Mage = 22.36; N = 331, Mage = 19.5), autonomous and controlling reasons appeared applicable to mastery-avoidance goals and regression and path analysis further showed that mastery-avoidance goals and their underlying autonomous reasons fail to predicted learning strategies over and above the pursuit of mastery-approach goals and their underlying reasons. Finally, need experiences were established as mediators between achievement motives and both mastery goals and their underlying reasons.