While in the late 1970s and early 1980s health compliance research on adults represented a vigorous field of study, a marked decline of interest on the topic set in during the last part of the 1980s. By contrast, research on health compliance involving pediatric populations was less popular during the same period; however, interest in this topic -- as evidenced by the contributions to this volume -- is on the increase. Four main themes -- relating to theory, measurement, prevention, and intervention -- emerge and are interwoven among the chapters. These themes help to bind and unify the volume into a conceptual whole because although the sections are divided along thematic lines, contributors often include elements of some or all of the themes in their chapters. This state of affairs reflects the interdependence of these thematic issues and suggests how important they are for the state of the art.