Because several experimental designs have been used to testthe effectiveness of self-talk interventions, the calculation of effect size had to be based on different formulas. Therefore, research designwas also tested as amoderator to identify possible method effects. Hunter and Schmidt’s (1994) meta-analytic approach was used. Further information regarding the calculation of the effect sizes, the coding of the moderators and the data analysis is presented in theAppendix.Afull list ofthe studies and the effect sizes included in the meta-analysis is presented in the online supplement at pps.sagepub.com/supplemental.