Few, if any, studies exist in which the helpfulness of particular responses in context have been evaluated by the involved clients or counselors due to the lack of an adequate method for obtaining evaluations of the impact of individual counselor responses. The development of Interpersonal Process Recall (IPR) provides a research tool which allows clients and counselors to describe the intentions, perceptions, impacts, and other experiences associated with specific interaction events. IPR was used in two studies to provide a measure of therapeutic effectiveness and to find predictors of response effectiveness. Clients rated two measures of response effectiveness as well as each counselor response on four measures of effectiveness. The client-counselor pair in which a response occurred was the best predictor of response effectiveness, with the perception of the person rating response effectiveness as the second best predictor. Generally, clients felt most benefited by nonquestioning or reassuring responses, while counselors felt most effective when reflecting or responding with the intent of guiding or explaining. (Author)