The World Health Organization’s recommendations on optimizing the roles of health workers aim to help address critical health workforce shortages that slow down progress towards the health-related Millennium Development Goals. A more rational distribution of tasks and responsibilities among cadres of health workers can significantly improve both access and cost-effectiveness – for example by training and enabling ‘mid-level’ and ‘lay’ health workers to perform specific interventions otherwise provided only by cadres with longer (and sometimes more specialized) training. These recommendations are intended for health policy-makers, managers and other stakeholders at a regional, national and international level. WHO hopes that countries will adapt and implement them to meet local needs. The recommendations were developed through a formal, structured process including a thorough review of available evidence. The process and the recommendations are described in the related documents.