This report draws on past and present peer-reviewed articles and published reports by institutions including the World Health Organization (WHO), the UK Department for International Development (DFID), and others to provide a scoping summary of the household-level spillovers and broader impacts of a select group of health initiatives. Rather than focusing on estimates of the direct health impacts of investments (e.g., reductions in mortality from vaccine delivery), we focus on estimates of the less-often reported spillover effects of specific health investments on household welfare or the broader economy. The brief is designed to give a concise overview of major theories linking health improvements to broader social and economic outcomes, followed by more in-depth summaries of available local- and country-level estimates of broader impacts, defined as project spillovers offering local, regional and national social and economic benefits not typically reported in project evaluations.