Violence is a global public health problem, and early childhood interventions are a core component of violence prevention programming. Interventions to support parents and teachers of young children can prevent violence against children by caregivers and prevent the early development of antisocial behavior. However, there is limited guidance on how to scale up these programs in low- and middle-income countries. In this article, we describe how we applied implementation science principles in the design, implementation, evaluation, and initial scaling of 2 complementary early childhood, violence prevention, caregiver training programs in Jamaica: the Irie Classroom Toolbox (a teacher-training program) and the Irie Homes Toolbox (a parenting program). We identified 7 implementation science principles most relevant to our work in scaling the Irie Toolbox programs and describe how these principles were operationalized in the Jamaican context. The principles are: (1) design programs for scale from the outset; (2) use learning cycles for quality improvement; (3) plan strategically for government agency adoption; (4) provide high-quality initial and ongoing training and regular supervision; (5) monitor implementation quality; (6) use flexible delivery modes; and (7) plan for program sustainment. Through applying these principles to scale the Irie Toolbox programs, we aim to promote a consistent approach to reducing violence against children, reducing child behavior problems, and increasing caregiver and child competencies across both home and school contexts at the population level. The principles and processes described in this article are relevant to other behavior change interventions in early childhood development, education, and public health. [Abstract copyright: Copyright © 2023 by the American Academy of Pediatrics.]