For over half a century, the Q-Sort has been administered to tens of thousands of individuals to quantify personality in a variety of clinical settings. Through the years, the test has been greatly enhanced by subsequent conceptual and methodological developments and has gained wide currency in research in hundreds of clinical settings. In this long-awaited expansion of his classic 1961 monograph, Jack Block traces the history of the Q-sort, from the early development of the CAQ descriptors, to the surprising results obtained in using the Q-sort in clinical psychology, and to current uses and future possibilities for research applications. Major versions of the Q-Sort currently in use are included, complete with instructions, reflections from the author"s personal experience, and descriptive "prototypes" for the individual sorter"s reference.