Adolescence is the period of transition between childhood and adulthood. It is generally considered to start with puberty, during which sexual maturation occurs and adolescents go through a spurt in g...Adolescence is the period of transition between childhood and adulthood. It is generally considered to start with puberty, during which sexual maturation occurs and adolescents go through a spurt in growth. In many children, however, puberty actually begins during the stage called pre-adolescence, which covers the ages 11 to 12 years. Puberty may begin before adolescence, but it usually continues for several years, well into the adolescent stage, which ends during the late teens.