This research integrated implicit theories of personality and the biopsychosocial model of challenge and threat, hypothesizing that adolescents would be more likely to conclude that they can meet the demands of an evaluative social situation when they were taught that people have the potential to change their socially relevant traits. Participants who received incremental interventions incremental-theory participants exhibited improved stress appraisals, more adaptive neuroendocrine and cardiovascular responses, and better performance outcomes. Students who received the intervention also had better grades over freshman year than those who did not. These findings offer new avenues for improving theories of adolescent stress and coping.