This manual seeks to provide practical advice to road safety practitioners on how to achieve a much higher proportion of users of two-wheeled vehicles wearing helmets. It follows on from the World report on road traffic injury prevention, which described evidence that setting and enforcing mandatory helmet use was an effective intervention for reducing injuries and fatalities among two-wheeler users. It is targeted at governments, nongovernmental organizations and road safety practitioners. The manual provides practical steps mainly on increasing helmet use among motorcycle users, though it also highlights case studies which illustrate issues around bicycle helmet use. Although aimed particularly at low-income and middle-income countries with low levels of helmet use, it is intended to be useful for all countries.