Sometimes referred to as teenage years, youth, or puberty, adolescence covers the period from roughly age 10 to 20 in a child's development.

In the study of child development, adolescence refers to the second decade of the life span, roughly from ages 10 to 20. The word adolescence is Latin in origin, derived from the verb adolescere, which means "to grow into adulthood." In all societies, adolescence is a time of growing up, of moving from the immaturity of childhood into the maturity of adulthood. Population projections indicate

that the percent of the U.S. population between the ages of 14 and 17 will peak around the year 2005.

There is no single event or boundary line that denotes the end of childhood or the beginning of...