The present large-scale quantitative study investigated the predictive effects of learning strategies and styles on Chinese undergraduate students' English achievement and their mediating effects on each other's relation to English achievement. A total of 439 students from different universities answered the 30-item Perceptual Learning Style Preference Questionnaire and 50-item Strategy Inventory for Language Learning as well as a background questionnaire. Analyses of the data revealed the following major findings: (a) Learning strategies were significantly positively related to learning styles, (b) both learning strategies and styles were significantly positively related to and predicted students' English achievement, and (c) learning strategies significantly mediated the relation between learning styles and English achievement. These findings clearly highlight the importance of learning strategies and styles in second/foreign language learning. Based on these findings, some implications are discussed.