The notion that "children represent the future" is an old one, but it has never been more true than today. Adolescents (defined in this journal as persons between childhood and adults—roughly age 10 to 24) make up fully 20 percent of the world's population, a larger proportion than ever before.

This demographic phenomenon arises at the same time that medical and social scientists are gaining increased understanding of the many changes that lie along the path between youth and adulthood. Disease or injury, violence or substance abuse, recklessness or exploitation—any number of events may imperil the body or the mind of a young person. At the same time, the physical and mental changes that mark adolescence present important opportunities for growth and development. Scientists now know that physical and emotional well being are essential for youngsters as they grow to become healthy, educated, contributing adult members of their societies.

This edition of eJournal USA examines many of the latest findings about the risks and challenges that young people face today and strategies and solutions for dealing with them. Experts discuss the medical, social, and environmental conditions that can harm our youths. And some famous young athletes who have fresh memories of adolescence tell us how they coped with problems they encountered on the journey to adulthood. The journal also provides rich bibliographic and Internet resources for additional exploration of the issue. We hope readers will be informed and sometimes inspired by what they find here.