<p> There is little research that examines differences in perceptions of need-supportive practices between teachers and students. In the current study, three research purposes were (1) to examine variabilities of teacher and student absolute or relative rating gaps in need-supportive practices, (2) to investigate the relations between absolute or relative rating gaps of teacher and student perceived need-supportive practices and student outcomes, and (3) moderating effects on the relations between teacher-student perceptions gaps of need-supportive practices and student outcomes. Participants were 581 5^th and 6^th students and their 29 teachers in Seoul, South Korea. Students completed questionnaires about teacher need-supportive practices, motivation, basic psychological needs (perceived autonomy, competence, and relatedness), and autonomous motivation. Teachers also answered questionnaires about their own need-supportive practices and autonomous motivation. One-way ANOVA and Tukey post-hoc tests were used to examine the variabilities of teacher and student rating gaps of need-supportive practices. Also, hierarchical linear modeling was employed to test the hypothesized models. Student sex and their beginning-of-year achievement were controlled for throughout the analyses.</p><p> The results showed that absolute rating gap for structure was significantly smaller than the absolute rating gaps for both autonomy support and involvement. Also, the relative rating gap for autonomy support was significantly smaller than the relative rating gap for both structure and involvement, but the relative rating gap of involvement was significantly larger than the relative rating gaps for autonomy support and structure. Regarding relations between rating gaps and student outcomes, a smaller teacher-student absolute rating gap for involvement was related to greater student autonomous motivation, and perceived competence and relatedness. Additionally, students with overestimating teachers tended to report lower student autonomous motivation, and low need satisfaction than students with underestimating teachers. Teacher autonomous motivation and teacher experience functioned as moderators.</p><p> The findings revealed the importance of reducing perception gaps between teachers and students about need-supportive practices. In particular, the findings showed the significance of perception gaps about involvement for student outcomes. In addition, the current study indicates the importance of examining both absolute and relative rating gaps between teachers and students.</p><p></p>