Drivers of success: improving implementation research tools for better health outcomes.

A thorough examination of context, and how it influences implementation of evidence-based interventions, is a promising strategy for enhancing child survival initiatives. Spreading approaches that are identified as drivers of successful reduction in under-five mortality from 'exemplar' countries could be pivotal in leading to reductions in other settings facing stagnant mortality rates, in particular for low- and middle-income countries with high disease burden and insufficient programmatic capacity to effectively implement evidence-based interventions at scale. Yet there remains a lack of robust analytic methods to accurately assess mortality and describe the drivers of interventions' implementation success at both national and subnational levels. The field of implementation science and its defining targets and tools is well positioned to address this knowledge gap by integrating qualitative and quantitative research methods into an adaptable evaluation framework that can be tailored to meet the specific needs across varying country contexts. These tools enhance the measurement of population health outcomes and provide crucial evidence on implementation barriers and facilitators that can inform policies that can be adjusted for diverse contexts. This commentary aims to emphasize the role of implementation research in understanding how exemplar countries achieved significant improvements in child survival and in identifying replicable lessons for other settings. Ultimately, all manuscripts underscore the relevance of implementation research in bolstering the reduction of under-five mortality.