The present study examined the extent to which middle school students' (N = 90) learning strategies mediated the relationship between their motivational orientations and academic achievement. Survey data revealed that higher degrees of intrinsic motivation predicted the use of both deep and surface learning strategies, whereas higher degrees of extrinsic motivation predicted the use of superficial strategies. Students' semester grade point averages indicated that academic achievement was negatively related to both extrinsic motivation and the use of superficial learning strategies, but surprisingly unrelated to intrinsic motivation and the use of deep learning strategies. As predicted, the negative relationship between extrinsic motivation and achievement was fully mediated by the use of superficial learning strategies.