Research in our field that explicitly emphasizes an objective of social impact in the most unprivileged parts of the world – the so-called global base of the pyramid (which refers to the 2.7 billion people living on less than $2.50 per day, the largest but most resource-poor economic group globally) has seen an increase in recent years. This trend seems to cut across the traditional application areas of OM and OR, and it coincides with an increased emphasis on environmental and social governance (ESG) values in industry, a greater prominence of the United Nations’ Sustainable Development Goals (UN SDGs) and increases in social impact research in other academic fields. In this paper, we pull together representative examples from our field of what we consider as social impact research aimed at improving living conditions at the base of the pyramid. We first examine the scale and scope of work published in Production and Operations Management over the last 25 years, and then provide a broader summary of the spectrum of research within OM and OR that constitute this stream of literature. We adopt the stance that OM and OR should embrace the current societal emphasis on social responsibility and positive social impact – and strive to contribute to the most pressing problems for those living at the base of the pyramid. Although our field has produced a body of work addressing such problems, individual research projects of this type are usually not viewed as falling under the broad umbrella of Social Impact Operations (SIO), but rather are classified as part of the closest application area. By providing an initial overview of this work we wish to celebrate the contribution of our field to this area, highlight common themes, catalyze a dialogue across application areas among researchers with a common perspective, and discuss opportunities for future research.