According to WHO, adolescents face a world of opportunities and dangers. They are at risk from many things and may find it difficult to get help from services designed for older people in settled relationships. But they can also be seen as the group that can learn to protect itself:

“In order for adolescents to take the risks that are important for their development and avoid those that will do them irreparable harm, their rights to health and development need to be fulfilled. This includes their rights to information and skills, a range of services, a safe and supportive environment, and opportunities to participate.

Frequently, this is not the case. HIV/AIDS flourishes where human rights are not protected. Adolescents are vulnerable because they often do not know how serious the problem of HIV/AIDS is, how it is caused or what they can do to protect themselves. Frequently they also do not have access to services that take their specific needs into consideration.

Some young people are particularly vulnerable. In countries where the predominant mode of transmission is by heterosexual sex, girls are often more vulnerable than boys, for both biological and social reasons.”

The author notes the importance (among other things) of:

• Involving young people in the development and implementation of programmes
  
  
• Using HIV/AIDS as an entry point for moving a broader adolescent health and development agenda – many other problems are linked to HIV/AIDS in terms of cause and effect, for example alcohol, drugs and violence, as are protective factors.

See WHO's publication “Adolescent Friendly Health Services” (789kb pdf).

The UN agency UNFPA has a section on Supporting Adolescents and Youth.

The Guttmacher Institute has some in-depth studies on sexual health

Youth International has a number of research articles on youth, Reproductive Health & HIV/AIDS.