Background: There is a significant gap between the prevalence of child and adolescent mental illness in Mexico and access to mental health services, especially those that are evidence-based. School-based interventions can significantly narrow this gap. Objective: The study evaluated the effectiveness of the interventions "Dejando Huellitas en tu Vida" (Leaving Traces on Your Life [Huellitas]) and "Criando con Amor, Promoviendo Armonía y Superación en México" (Raising Children with Love, Promoting Harmony and Self-Improvement [CAPAS-Mx]). Methods: Participants were 215 caregivers (M[subscript age] = 38.4 years, SD = 8.9, 82.9% women) and 202 children (M[subscript age] = 8.6 years, SD = 1.3, 44.06% girls) from four public schools randomly assigned to four experimental conditions (Huellitas, CAPAS-Mx, Huellitas-CAPAS-Mx, and Control) with pre-test and post-test assessments. Results: Caregivers in the multicomponent condition reported significantly lower scores in child externalizing problems and higher scores in discipline, skills encouragement, social adaptation, emotional control and prosocial behavior than caregivers in the control group. There were also improvements in parents' use of effective discipline and skills encouragement in the CAPAS-Mx group over the control group. Among the children, only those in the Huellitas condition showed a decrease in mediation. Conclusions: Findings support the implementation of the multicomponent intervention in public school settings.