Emerging Themes in Cognitive Development, Volumes I and II offer the full spectrum of current knowledge and research trends in cognitive developmental psychology. The first volume provides a foundation by describing key discoveries in new areas of research and by thoroughly examining fundamental aspects of the field, including several demonstrations of formal modeling; the gains in prediction and precision that can be won by such mathematical analyses are the hallmark of cognitive development as a maturing science. The second volume traces the development of cognitive competence - denoting a change or increment in cognitive proficiency, understanding, or mastery - and includes analyses of innovative and previously unpublished studies. The primary challenge issued by many of the authors in this volume is to ensure the incorporation of new knowledge into educational practices. These volumes, which are milestones in cognitive developmental psychology, interest every researcher in the field.