The study examined the incremental validity of thinking styles in predicting academic achievement after controlling for personality and achievement motivation in the hypermedia-based learning environment. Seventy-two Chinese college students from Shanghai, the People's Republic of China, took part in this instructional experiment. The End-Of-Semester test was designed to examine the students' achievement in the course of General Psychology. The results partially supported the hypotheses concerning the relationships between students' Type I and II thinking styles and their academic achievement in Type I test (including analysis, problem-solving, and essay tests) and Type II test (including multiple-choice and cloze tests), and showed that some Type III styles were significantly related to their academic achievement. Hierarchical regression analysis indicated that the capacity of thinking styles for explaining and predicting academic achievement was sometimes over and above the sum of personality traits and achievement motivation. Implications for educational practice are discussed. (Contains 4 tables.)