A meta-analysis of prior studies of techniques designed to induce mail survey response rates was conducted. Research encompassing 184 effects (study outcomes) in 115 studies (articles) for 17 predictors of response rate was examined. The average effect size across all manipulations was r=.065, indicating an average increase of about 6.5 percent in response rates for manipulations. Effect sizes for specific predictors and two potential moderators of effects were examined. Results indicated that repeated contacts in the form of preliminary notification and follow-ups, appeals, inclusion of a return envelope, postage, and monetary incentives, were effective in increasing survey response rates. Significant effect sizes for the predictors ranged from an increase in response of 2 percent to 31 percent. Implications of the results for the conduct of mail surveys and future research on mail survey response behavior are discussed.