ABSTRACT
For readers of this book who are 30 years or older(!) the world we now live in is very different from the world when we were teenagers, and it is likely to continue to change at a rapid pace throughout this century. The social profile and adolescent trajectory is changing. As a result, adolescence is becoming a more complex life stage, longer in duration, and (potentially) more risky, with new rights and responsibilities for young people themselves. Adolescents constitute a significant percentage of the population, have a distinct pattern of health and illness, and are one subset of the general population that has experienced little or least improvement in overall health status over the past 40 years.
