Michigan State University operationalized an existing conceptual curriculum based on an infant mental health approach. The curriculum was previously developed with a partner Early Head Start (EHS) program. Specifically, this study developed a relationship-based curriculum with manualized curricular activities that target social-emotional development in infants and toddlers. Participants included approximately 140 low-income families from two home-based EHS programs. Phase 1 of the study focused on the development, implementation, and validation of the manualized curriculum. Using a quasi-experimental design, half of the home visitors at each site implemented the curriculum. Data collection methods included focus groups, child assessment, parent and staff self-report, and observations. The expected outcome of this study was the development of an evidence-based curriculum, manualized curriculum, including guidelines, training, implementation strategies, and a report on the theoretical basis for the curriculum.