The education goal-Goal 4-of the 2030 UN Sustainable Development Goals places a strong emphasis on "ensuring inclusive and equitable quality education and promoting life-long learning opportunities for all." This goal recognizes that though great gains have been made in improving access to education in the two decades since the first set of UN goals in the year 2000-a major accomplishment-such success is not enough. Schooling must be of good quality and effective learning for all children, and in all locales. The achievement of quality education has been especially difficult for those who are poor and marginalized in low-income countries-those at the bottom of the pyramid.This volume-Learning, Marginalization, and Improving the Quality of Education in Low-income Countries-is based on papers presented at an international virtual conference, Learning at the Bottom of the Pyramid 2 (LBOP2), held online in November/December 2020, and co-hosted by the University of Pennsylvania and IIEP-UNESCO. About 150 experts and observers-including researchers, policymakers and practitioners-participated in the conference. Topics included both thematic issues (e.g., metrics and financing) and national case examples (India, Ivory Coast, Kenya and Mexico), which broadly focused on better understanding children's learning in low-resourced settings worldwide, along with ways that new policy approaches can improve learning.This volume is the second in a series on "learning at the bottom of the pyramid." The first conference, LBOP1, was held at the University of Pennsylvania in Philadelphia on March 2-3, 2017, and resulted in the 2018 book Learning at the bottom of the pyramid: Science, measurement and policy in low-income countries, published by IIEP-UNESCO.The LBOP initiative continues to raise substantial issues of concern to international agencies, foundations, policymakers, education vi Learning, Marginalization, and Improving the Quality of Education specialists, and the public at large. It is clear that in order to achieve quality education for all, a better understanding of learning in lowincome societies will remain a high priority.