Many hypotheses have been put forth to explain the under-representation and under-performance of historically marginalized racial and ethnic minority students in physics. While much research has focused on the relations between prior knowledge and performance, less work has examined the potential interactive role of student motivation. In particular, expectancy value theory posits that students' beliefs about their expectations for success (e.g., self-efficacy) and the value they associate with

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... an academic task (e.g., intrinsic interest) influence their persistence and performance. In this study, we conducted a longitudinal analysis of students' motivational characteristics in introductory physics courses by administering surveys at three points during the year. White, Asian, and underrepresented racial/ethnic minority students' self-efficacy and interest in physics are reported, and implications for instruction are discussed. I. edited by Ding, Traxler, and Cao; Peer-reviewed,