Peer education is an approach to health promotion, in which community members are supported to promote health-enhancing change among their peers. Peer education is the teaching or sharing of health information, values and behavior in educating others who may share similar social backgrounds or life experiences. Rather than health professionals educating members of the public, the idea behind peer education is that ordinary lay people are in the best position to encourage healthy behaviour to each other. Areas of application Peer education has become very popular in the broad field of HIV prevention. It is a mainstay of HIV prevention in many developing countries, among groups including young people, sex workers, people whom practice unprotected sex, or people who use intravenous drugs. Peer education is also associated with efforts to prevent tobacco, alcohol and other drug use among young people. Peer educators can be effective role models for young adolescents by promoting healthy behavior, helping to create and reinforce social norms that support safer behaviors, and also serve as an accessible and approachable health education resource both inside and outside the classroom. Peer education is useful in promoting healthy eating, food safety and physical activity amongst marginalized populations. Peer education is also favorably used in medical education. Some public school districts have implemented peer-education programs. For example, New York City schools implemented a peer-led sex education program in 1974. The process A peer education programme is usually initiated by health or community professionals, who recruit members of the target community to serve as peer educators. The recruited peer educators are trained in relevant health information and communication skills. Armed with these skills, the peer educators then engage their peers in conversations about the issue of concern, seeking to promote health-enhancing knowledge and skills. The intention is that familiar people, giving locally-relevant and meaningful suggestions, in appropriate local language and taking account of the local context, will be most likely to be able to promote health-enhancing behaviour change. There is a great variety in the support provided to peer educators. Sometimes they are unpaid volunteers, sometimes they are given a small honorarium, sometimes they receive a reasonable salary. The peer educators may be supported by regular meetings and training, or expected to continue their work without formal supports. Theories A variety of theories are offered regarding the question of how peer education is supposed to achieve positive results. Kelly's popular opinion