This article offers four key lessons learned from a set of seven studies undertaken as part of the collection entitled, "Improving Maternal Health Measurement to Support Efforts toward Ending Preventable Maternal Mortality". These papers were aimed at validating ten of the Ending Preventable Maternal Mortality initiative indicators that capture information on distal causes of maternal mortality. These ten indicators were selected through an inclusive consultative process, and the research designs adhere to global recommendations on conducting indicator validation studies. The findings of these papers are timely and relevant given growing recognition of the role of macro-level social, political, and economic factors in maternal and newborn survival. The four key lessons include: 1) Strengthen efforts to capture maternal and newborn health policies to enable global progress assessments while reducing multiple requests to countries for similar data; 2) Monitor indicator "bundles" to understand degree of policy implementation, inconsistencies between laws and practices, and responsiveness of policies to individual and community needs; 3) Promote regular monitoring of a holistic set of human resource metrics to understand how to effectively strengthen the maternal and newborn health workforce; and 4) Develop and disseminate clear guidance for countries on how to assess health system as well as broader social and political determinants of maternal and newborn health. These lessons are consistent with the Kirkland principles of focus, relevance, innovation, equity, global leadership, and country ownership. They stress the value of indicator sets to understand complex phenomenon related to maternal and newborn health, including small groupings of complementary indicators for measuring policy implementation and health workforce issues. They also stress the fundamental ethos that maternal and newborn health indicators should only be tracked if they can drive actions at global, regional, national, or sub-national levels that improve lives.