The goal of this book is to characterize the nature of abilities, competencies, and expertise, and to understand the relationship between them. While some psychologists see these sets of skills as rather distinct, others view them on a continuum with abilities developing into competencies and competencies developing into expertise. This book integrates into a coherent discipline what formerly have been, to a large extent, three separate disciplines by articulating the interrelationships between abilities, competencies, and expertise.