Epidemiology is a scientific discipline dating back about 150 years. During this period it has contributed enormously to our understanding of the causes of disease and to the identification of strategies for their prevention. Unfortunately, epidemiologists have been less successful in ensuring that the epidemiological information so exquisitely gathered is translated into effective policies and programmes. Epidemiologists have failed to actively contribute to improving the health of populations we serve, especially poor and disadvantaged populations. The case of non-communicable diseases (NCD) is instructive. Two in every 3 of the 57 million deaths worldwide each year are due to NCD, principally cardiovascular diseases, cancers, diabetes and chronic respiratory diseases; NCD death rates are now higher in poor than in wealthy countries and among poor people in all countries. The UN High-Level Meeting on NCD in September 2011 stems from the global NCD crisis and the need for a coordinated and effective response. If this meeting results in a positive outcome, it will be in part because of the contribution by epidemiologists in mapping the NCD pandemic and identifying its causes. However, a successful outcome will result only if we engage with the political dimensions of disease prevention and treatment. The steps required in translating the epidemiology of NCD into simple, focused and politically acceptable messages have not been easy and have taken epidemiologists into areas for which we are remarkably unskilled, but which provide important lessons for the future of epidemiology.