Abstract
An important part of evidence‐based practice is to include client preferences in the treatment decision‐making process. However, based on previous reviews of the literature there is some question as to whether including client preferences actually has an effect on treatment outcome. This meta‐analytic review summarized data from over 2,300 clients across 26 studies comparing the treatment outcome differences between clients matched to a preferred treatment and clients not matched to a preferred treatment. The findings indicate a small significant effect (r=.15, CI~.95~: .09 to .21) in favor of clients who received a preferred treatment. The binomial effect size indicated that matched clients have a 58% chance of showing greater improvement, and further analysis indicate that they are about half as likely to drop‐out of treatment when compared with clients not receiving a preferred treatment. Study design was seen to be a moderating variable in that partially randomized preference trials may underestimate the treatment preference effect. Implications for best practice standards are discussed. © 2009 Wiley Periodicals, Inc. J Clin Psychol 65:1–14, 2009.