First published in 2001. The purpose of this issue is to demonstrate the advantages of meta-analysis in summarizing research in special education. Toward this end, five articles are included in this issue that deal with methodology, interpretation, and application of meta-analyses. The first article is a brief primer on meta-analysis that compares and contrasts it with more traditional review methods and describes the methodological procedures for conducting a quantitative research synthesis. The second article, summarizes findings from 24 meta-analytic efforts. The third article explores the important issue of face validity: Can we be confident about the findings from meta-analyses? The fourth article examines the controversy surrounding the meta-analysis of single-participant research: What is the best metric? The final paper reviews the process of decision making in special education by showing how meta-analytic findings can provide a comprehensive knowledge base that, combined with wisdom and experience, can be used to decide whether to include particular interventions.