Youth are not a homogenous group – they are comprised of unique individuals with unique needs. Not all youth are in the same stage of life, even though we may consider them young. 

For example, adolescence is defined by the World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF) as between 10-19 years with two distinct stages: early adolescence (ages 10-14) and late adolescence (ages 15-19). These age spans relate to some of the most significant physical and psychological changes in a person’s development. 

Not only are very young adolescents distinctly different than older adolescents and young adults, but gender differences are pronounced. Adolescent boys and young men experience their transition into adulthood differently that adolescent girls and young women, not just through biological experiences such as puberty, but by virtue of their growth and development being facilitated by specific culture norms that shape their preferences, attitudes, and behaviors. 

Age and gender—although the most obvious differentiators—are not the only ways that young people can be diverse. Youth experience many different factors that may affect them, including socioeconomic status and marital status. Some youth are moving in and out of educational systems, getting and leaving various jobs, learning to grow up, becoming parents, or living without parents. Some youth identify as lesbian, gay, bisexual transgendered, and intersex (LGBTI)—a population with increased health risks and few opportunities for support during their transition to adulthood. 

Vulnerable or marginalized youth populations are those that, for any reason, tend to be excluded from “universal” youth programming that could benefit them. These populations are often not specifically targeted for youth-focused programming. Programs and policies should consider the needs of the young population they serve. Conducting a youth assessment before implementation can help understand the unique and diverse needs of their beneficiaries and help to ensure planning is tailored to all youths’ needs. 

The resources in this section present some of the existing evidence on key populations among young people, along with promising practices in implementation and evaluation. 

Adolescent Boys

Adolescent Girls

Lesbian, Gay, Bisexual, Transgendered and Intersex (LGBTI) Youth

Out of School Youth

Child, Early and Forced Marriage

Orphans and Vulnerable Youth

Very Young Adolescents