This text offers an integrated treatment of the central themes in the contemporary study of adolescence - development, diversity, context, and application. Specifically, it enables students to understand the bases of the developmental changes young people experience during the adolescent period; to appreciate the important instances of diversity to recognize the important role played in adolescent development of the different instances of the context, or ecology, of human development, and to understand the ways in which knowledge about adolescent development, diversity, and context may be applied to promote positive development among young people. This integration of themes helps students appreciate the dynamic character of the field of adolescent development today.