Although the basic growth changes for teenagers are the same as they were 20 or 30 years ago, the environment in which these changes occur has changed. This book describes the characteristic changes in human behavior which take place from year to year between the ages of 10 and 14. Part 1 of the book describes the longitudinal research, which allowed a comparison of teenagers today with those during the 1970s. Part 2 of the book presents maturity profiles and maturity traits in areas including emotions, school life, and ethical sense for adolescents in each year from ages 10 through 14. Part 3 of the book presents trends in each of the maturity trait areas, and selected growth gradients, including likes and dislikes, same-sex friends, risk behaviors, and teacher-child relationships. Part 4 discusses briefly developmental changes that occur during ages 15 and 16. Sources of information, tables of findings from the study and chapter notes are appended. (HTH)