Introduction: This study examined associations between adolescents' daily negative and positive events and their coping efficacy, an understudied topic but pivotal to adolescent thriving. Methods: The sample included 153 parent-adolescent triads; adolescents' mean age, 15.71 years (SD = 1.53), 51% girls. Parents were in their midlife (Mage mother = 47.82, SD = 4.90; Mage father = 50.39, SD = 5.80). The study used a daily diary methodology to test within-person links to establish a temporal order of effects. Over seven consecutive days, adolescents reported on 14 daily negative and positive events. Adolescents, mothers, and fathers reported on adolescents' daily coping efficacy. Results and Conclusions: Multilevel latent profile analysis (MLPA) identified 4 day-level event profiles: "low event day" (34% of days), reflecting low levels of both positive and negative events and low coping efficacy and positive and negative mood; "positive day" (44%), reflecting dominance of intense positive events and corresponding high coping efficacy and positive mood; "mixed day," reflecting a combination of intense positive and negative events with average coping efficacy and positive mood despite high negative mood and impaired coping. Multilevel path analysis showed adolescents reported increased coping efficacy a day after increased academic load, and parents reported increased adolescent coping efficacy a day after positive parent-adolescent interactions. Fathers reported decreased adolescent coping efficacy a day after peer disappointment. Findings suggest positive events predominate in adolescents' lives, and their coping efficacy is sensitive to dynamic changes in the valence of context.