Young people aged 10–19 make up almost 20 percent of the population in less developed regions. This vast, highly diverse population faces a variety of threats that could disrupt their healthy transition to adulthood, including early marriage and childbearing, school leaving, violence, exploitation, unemployment, and HIV/AIDS. The majority of youth programs fail to reach the most vulnerable; most programs are only accessible to those with greater levels of social and human capital, such as an education or friendship networks. Promoting Healthy, Safe, and Productive Transitions to Adulthood Brief No. 28 describes how the Population Council, recognizing the need for generating evidence to target vulnerable subgroups of young people effectively, developed the Coverage Exercise (CE) tool to assess the equity of access to programs for adolescents. CE is a relatively low-cost tool used to yield data on the demographic characteristics of the clients of a particular youth service, group of service providers, or organizations operating within a particular geographic area.