Although teachers' autonomy support and structure are considered essential elements of the classroom environment to promote effective learning strategies, prior research has sometimes provided conflicting results. This inconsistency may stem from how autonomy support and structure relate to some outcomes but not others. Alternatively, this variability might be attributed to nonlinear relations, which have been scarcely tested thus far. In this cross-sectional study, we revisited this issue by examining both the linear and curvilinear relations of autonomy support and structure to challenge-seeking, novelty avoidance, and procrastination. Participants were 3,271 adolescents (M[subscript age] = 15.91, SD = 0.34 years; 59.8% females) from 116 classrooms. Multilevel polynomial regression analyses revealed that, compared to structure, autonomy support was a more reliable predictor of challenge-seeking, both at the student and the classroom levels. In contrast, structure predicted novelty avoidance and procrastination more reliably at both levels than autonomy support. Response surface analyses indicated that the most desired pattern existed at the line of congruence. Our findings suggest that both autonomy support and structure are needed to enhance students' learning strategies. However, the degree of necessity may vary for specific outcomes, with one potentially being more crucial than the other.