At the onset of the Sustainable Development Goals, in 2015, a group of global health experts delivered a call to action for an improved measurement system for women’s and children’s health. Five principles were defined, including having a focused set of core indicators, making data relevant to countries, investing in innovations, embedding equity measures and supportive global leadership. Five years later, in 2020, a second meeting reviewed progress against these principles and identified gaps and opportunities for investment in the coming decade.