Introduction to the special section on multivariate psychotherapy process research: structure and change in the talking cure.

In response to the search for novel investigative strategies to apply in the study of psychotherapy processes, several investigators have turned to the use of factor-analytic methods of investigation. Four studies are presented that use such methods to investigate the structure of, and change in, aspects of the client and therapist discourse and symptoms over the course of treatments. The corpora of process data, culled from investigations taking place on three different continents, represent some of the largest samples of in-therapy behavior that have been analyzed in microanalytic detail. Providing both methodological advances and important substantive findings, the studies included were conducted to stimulate further use and development of factor-analytic methods to identify and track key processes over the course of psychotherapeutic treatment.