The brief from MOMENTUM Routine Immunization Transformation and Equity explores a behavior-focused methodology to enhance health worker performance in routine immunization services in Kenya. By employing behavior integration—a human-centered approach—the project identifies and addresses systemic barriers, such as inadequate training, limited resources, and poor community engagement, to improve immunization coverage. The initiative emphasizes co-creation, local ownership, and sustainability, enabling health workers and managers to adopt practices that enhance service quality and client experiences. This approach offers practical solutions to overcome entrenched challenges, fostering equitable access to life-saving vaccines.