This article reviews research conducted on the interpersonal influence process in counseling, specifically those studies relating to counselor expertise, attractiveness, and trustworthiness. The review is organized and analyzed in terms of variables affecting the client's perception of critical counselor characteristics and effects of the variables on the counselor's ability to influence the client. Evidence is presented to suggest that a wide range of events cue clients' perceptions of counselor expertise, attractiveness, and trustworthiness. Results from studies are also presented which found that when sources of counselor expertness are combined, the counselor's ability to influence a client's opinion is increased. Future research problems and methodologies are discussed in terms of theory construction, recent research from social psychology, and internal/external validity. (Author)