It is well-established that culture and language are interrelated. The concept of integrating culture into language teaching is widely accepted. The purpose of this study was to investigate the motivational change of Taiwanese university students taking English classes which American culture topics were integrated into. The study participants were students at a selected university in northern Taiwan. Two freshmen English classes, a total of 80 students, were randomly assigned into either the control group or the experimental group. The experimental group received cultural instruction two hours a week for one semester, while the control group did not. Data were collected and analyzed using quantitative methods. The instruments used included questionnaires. Results confirmed that the integration of culture arouses students' English learning motivation, especially integrative motivation. Students indicated that the use of American culture topics in class can facilitate their English learning. It was revealed that cultural teaching was effective in changing students' motivation and their attitudes toward English learning. Findings derived from the study led to the conclusion that integrating American culture topics into university English classes yielded positive motivational changes in students' English learning.