Summary: The Countdown to 2015 for Maternal, Newborn, and Child Survival monitors coverage of priority interventions to achieve the Millennium Development Goals (MDGs) for child mortality and maternal health. We reviewed progress between 1990 and 2010 in coverage of 26 key interventions in 68 Countdown priority countries accounting for more than 90% of maternal and child deaths worldwide. 19 countries studied were on track to meet MDG 4, in 47 we noted acceleration in the yearly rate of reduction in mortality of children younger than 5 years, and in 12 countries progress had decelerated since 2000. Progress towards reduction of neonatal deaths has been slow, and maternal mortality remains high in most Countdown countries, with little evidence of progress. Wide and persistent disparities exist in the coverage of interventions between and within countries, but some regions have successfully reduced longstanding inequities. Coverage of interventions delivered directly in the community on scheduled occasions was higher than for interventions relying on functional health systems. Although overseas development assistance for maternal, newborn, and child health has increased, funding for this sector accounted for only 31% of all development assistance for health in 2007. We provide evidence from several countries showing that rapid progress is possible and that focused and targeted interventions can reduce inequities related to socioeconomic status and sex. However, much more can and should be done to address maternal and newborn health and improve coverage of interventions related to family planning, care around childbirth, and case management of childhood illnesses.