Remarkable financial and political efforts have been focused on the reduction of child mortality during the past few decades. Timely measurements of levels and trends in under-5 mortality are important to assess progress towards the Millennium Development Goal 4 (MDG 4) target of reduction of child mortality by two thirds from 1990 to 2015, and to identify models of success. This study is published by The Lancet look at the progress of UN Millennium Development Goals 4 and 5 on lowering child and maternal death rates in developing countries.