The mental health treatment gap for children and adolescents worldwide calls for implementation science research to help bring evidence-based interventions into practice. Given the near absence of services specific to child and adolescent mental health in both high-income and low- and middle-income countries, we recommend that implementation research for child and adolescent mental health extend beyond mental health clinics and primary care settings and focus on implementing, adopting, and sustaining integrated interventions from prevention to treatment, delivered by lay health workers, across sectors. We depict through selected examples what this research looks like in practice, highlight gaps in implementation research specific to children and adolescents, and make recommendations for future research. Child and adolescent focused mental health research informed by an implementation framework can generate effective solutions and increase the well-being of children worldwide.