BackgroundEvidence-based medicines, technologies, and protocols exist to prevent many of the annual 300,000 maternal, 2.7 million neonatal, and 9 million child deaths, but they are not being effectively implemented and utilized in rural areas. Nepal, one of South Asia’s poorest countries with over 80% of its population living in rural areas, exemplifies this challenge. Community health workers are an important cadre in low-income countries where human resources for health and health care infrastructure are limited. As local women, they are uniquely positioned to understand and successfully navigate barriers to health care access. Recent case studies of large community health worker programs have highlighted the importance of training, both initial and ongoing, and accountability through structured management, salaries, and ongoing monitoring and evaluation. A gap in the evidence regarding whether such community health worker systems can change health outcomes, as well as be sustainably adopted at scale, remains. In this study, we plan to evaluate a community health worker system delivering an evidence-based integrated reproductive, maternal, newborn, and child health intervention as it is scaled up in rural Nepal.MethodsWe will conduct a type 2 hybrid effectiveness-implementation study to test both the effect of an integrated reproductive, maternal, newborn, and child health intervention and the implementation process via a professional community health worker system. The intervention integrates five evidence-based approaches: (1) home-based antenatal care and post-natal care counseling and care coordination; (2) continuous surveillance of all reproductive age women, pregnancies, and children under age 2 years via a mobile application; (3) Community-Based Integrated Management of Newborn and Childhood Illness; (4) group antenatal and postnatal care; and 5) the Balanced Counseling Strategy to post-partum contraception. We will evaluate effectiveness using a pre-post quasi-experimental design with stepped implementation and implementation using the RE-AIM framework.DiscussionThis is the first hybrid effectiveness-implementation study of an integrated reproductive, maternal, newborn, and child health intervention in rural Nepal that we are aware of. As Nepal takes steps towards achieving the Sustainable Development Goals, the data from this three-year study will be useful in the detailed planning of a professionalized community health worker cadre delivering evidence-based reproductive, maternal, newborn, and child health interventions to the country’s rural population.Trial registrationClinicalTrials.gov Identifier: NCT03371186, registered 04 December 2017, retrospectively registered.