Since its 1947 founding, ETS has conducted and disseminated scientific research to support its products and services, and to advance the measurement and education fields. In keeping with these goals, ETS is committed to making its research freely available to the professional community and to the general public. Published accounts of ETS research, including papers in the ETS R&D Scientific and Policy Contributions series, undergo a formal peerreview process by ETS staff to ensure that they meet established scientific and professional standards. All such ETS-conducted peer reviews are in addition to any reviews that outside organizations may provide as part of their own publication processes. Peer review notwithstanding, the positions expressed in the ETS R&D Scientific and Policy Contributions series and other published accounts of ETS research are those of the authors and not necessarily those of the Officers and Trustees of ETS. In 2010, we began to synthesize these scientific and policy contributions, with the intention to release a series of reports sequentially over the course of the next few years. These reports constitute the ETS R&D Scientific and Policy Contributions Series.In the sixth report in the series, Tim Moses examines the contributions to the psychometric study of test scores made by Educational Testing in the past 60 years since the founding of the organization. These contributions can be roughly organized into three areas. The first area, the measurement properties of tests and developments of classical test theory, covers ETS contributions that provide culminating and progressively more rigorous formalizations of classical test theory. These contributions and others by ETS researchers in this area have led to improvements in the psychometric (measurement) quality of tests. The second area is the use of tests as predictors in correlational and regression relationships. ETS contributions in this area have helped to define appropriate and valid uses for tests. The third area is the integration and application of measurement theories and correlational and regression analyses to address testscore issues, which is relevant to operational work on testing programs.This report complements two other upcoming reports on psychometrics in the ETS R&D Scientific and Policy Contributions series, one of which by Neil Dorans will focus on fairness and another by James Carlson that will focus on items.