This paper presents an account of the impact that research synthesis methods, in the form of psychometric meta-analysis, has had on industrial/organizational (I/O) psychology. This paper outlines the central contributions of psychometric meta-analysis in providing a method for developing cumulative knowledge. First, this paper describes the concerns and the state of the field before the development of meta-analytic methods. Second, the paper explains how meta-analysis addressed these concerns. Third, the paper details the development of psychometric meta-analysis through VG research and describes how the use of psychometric meta-analysis spread to other topic areas in the field. Finally, the paper presents illustrative example literatures, such as training and leadership, where meta-analysis had crucial impacts. Copyright © 2011 John Wiley & Sons, Ltd.