Effective regulation of motivation can be theoretically explained by both the extent of motivational regulation strategies used (quantity) and their optimal implementation (quality). Researchers have not yet analysed the significance of both aspects for learning success simultaneously. In the present study, 188 students were presented with different descriptions of prototypical learning situations paired with specific causes for poor motivation and were asked to report both the quantity and key aspects of the quality of motivational regulation strategies they would implement. Regression analyses revealed that the quantity of strategy use was a moderate positive predictor of both self-reported regulatory effectiveness and self-reported effort while studying. These two dependent variables were significantly better predicted by including the quality of strategy use. Moreover, only the quality of strategy use correlated with academic achievement. Structural equation modelling indicated that the effect of strategy quality on academic performance was mediated by regulatory effectiveness and effort.