This study examined physiological and coping responses to peer-evaluative challenges in early adolescence as predictors of academic outcomes. The sample included 123 young adolescents (X-bar[subscript age]) = 12.03 years) who participated in the summer before (T1) and the spring after (T2) the transition to middle school. At T1, respiratory sinus arrhythmia reactivity (RSAR) and engaged coping responses (prosocial problem-solving, positive cognitive appraisals) were assessed in real-time during lab-based simulations of peer-evaluative challenges. Academic performance was assessed with multiple informants (teachers, parents, adolescents) at T1 and T2. Parents provided reports about academic adjustment to middle school at T2. RSAR significantly predicted improved academic performance between T1 and T2 and positive academic adjustment at T2. Engaged coping was marginally associated with improved academic performance and significantly associated with positive academic adjustment; these results were partially corroborated by analyses with an alternative measure of engaged coping (engaged planning), which significantly predicted improved academic performance.