In this article, the authors present a multilevel (or hierarchical linear) model that illustrates issues in the application of the model to data from meta-analytic studies. In doing so, several issues are discussed that typically arise in the course of a meta-analysis. These include the presence of non-zero between-study variability, how multiple effect sizes per studies can be combined into a single analysis, and an examination of model misfit and robustness in an attempt to understand the effects of treatments on multiple outcomes. The authors' purpose is to explain the model and illustrate analytic strategies with a well-known data set. The results reported in this study are based on a set of 177 studies (containing 454 effect sizes) of systematic desensitization, behavior modification, and cognitive-behavioral (CB) comparisons from the original study by Smith, Glass, and Miller (1980). On the basis of this analysis of the Smith et al. data, it is concluded that interventions based on CB theory have been moderately effective in improving outcomes, whereas interventions based on behavior modification and systematic desensitization may have had negligible effects. A list of SAS Codes is appended. (Contains 3 figures and 4 tables.)