In this study I examined how Taiwanese junior high school students' perceptions of autonomy support were related to their motivational characteristics, and the ability of these constructs to explain students' academic engagement. A total of 343 eighth-grade students completed a self-report survey assessing their perceptions of autonomy support from teachers, achievement goal orientations, self-regulatory styles, and behavioral as well as emotional engagement in schoolwork. Results supported the contention of self-determination theory (SDT) that, when students learn out of personal interest and personal relevance, they are more fully engaged in schoolwork, both behaviorally and emotionally. Moreover, students who perceived higher levels of autonomy support provided by teachers also reported more adaptive patterns of learning. In terms of effects of achievement goals, results suggested that, when constructs from SDT were accounted for, mastery-approach and performance-avoidance goals remained important for explaining Taiwanese students' academic functioning. This study also documented profiles of behaviorally engaged students with different levels of emotional engagement. Findings showed that behaviorally engaged students with higher levels of emotional engagement reported higher perceptions of autonomy support from teachers, identified regulation, intrinsic motivation, and mastery-approach goal orientation than did behaviorally engaged students with lower levels of emotional engagement. Implications for education and future research are discussed. (Contains 5 tables.)