This document is written by The American Psychological Association (APA) in response to numerous requests by professionals in various fields for help in understanding and working with adolescents who have a need for substantive knowledge about the trajectory of youngsters’ lives from late elementary school ages through high school years. Sections of this publication refer to parenting that will be more or less relevant depending on one’s needs. The same is true with regard to topics which will be more or less relevant depending on the reader’s context and needs.