Tanya Marchant, Zulfiqar A Bhutta, Robert Black, John Grove, Catherine Kyobutungi, Stefan Peterson
Summary: This editorial accompanies a 6-paper supplement emerging from a 2018 RMNCAH-N measurement conference in South Africa organized by Countdown 2030. The papers share two common calls for measurement: 1) the need for greater harmonization of measurement standards and 2) the need for investing in further development of measurement tools and methods.