Kingston and Nash (2011) recently presented a meta-analysis of studies showing that the effect of formative assessment on K-12 student achievement may not be as robust as widely believed. This investigation analyzes the methodology used in the Kingston and Nash meta-analysis and provides further analyses of the studies included in the study. These analyses suggest, consistent with other reviews, that some of the conclusions reached by Kingston and Nash may not be credible. The studies used in the Kingston and Nash meta-analysis were limited by the nature of the selection process, the questionable quality of their methodologies, and the multiple ways formative assessment was defined and operationalized, often without inclusion of recognized formative assessment characteristics that are needed for successful practice. These limitations mitigate Kingston and Nash’s conclusion that the median effect size of experimental studies reviewed suggests a much smaller overall impact than reported by others. Recommendations for further research in this area are summarized to establish an improved body of literature on the effects of formative assessment on student achievement. Accessed 16,036 times on https://pareonline.net from February 19, 2013 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right.