Direct Instruction’s Reading Mastery curriculum is a comprehensive core reading program that has been found, in decades of research, to be highly effective. Yet, the WWC’s 2008 review of Reading Mastery concluded that no studies met their evidence standards and they were “unable to draw any conclusions based on research” regarding its effectiveness. A careful examination of the research cited by the WWC found that this conclusion was not well founded. The WWC failed to examine close to 100 research studies that were cited in other well-known reviews of the literature. In addition, reviews of studies that were included were flawed. For instance, one large, well-regarded study was rejected because training of teachers to use the curriculum was considered a “confound” to the use of the curriculum itself. Other studies were dismissed because the treatment (Reading Mastery) and control groups were unequal at baseline. Yet, these differences were statistically controlled and, in two cases, the treatment groups had lower pretest scores but equal and higher posttest scores. Examination of reviews of other curricula indicates that at least some of the material posted on the website is misleading. Summaries do not reflect the conclusions of the articles and, in at least one case, are exactly opposite to the published conclusions. Attempts have been made to communicate these concerns and recommendations for change to the WWC and Mathematica Policy Research, Inc., which administers the Clearinghouse. These concerns and suggestions, which parallel those of other researchers, have been rejected. Given the very serious problems in the review procedures and policies, the NIFDI research staff suggests extreme caution in the use of any ratings or conclusions from the WWC.