Validation studies of quantitative measures are noticeably absent from mathematics education journals too, which presents the challenge of determining whether an instrument is appropriate for a given study, much less whether its interpretations and results will be useful for analysis. In order for research in mathematics education to become more cumulative and to build on previous research, research instruments need to be widely shared, easily accessible, consistent in their intended use, and uniform in the interpretation of scoring. The American Statistical Association’s report on Use of Statistics in Mathematics Education Research states: If research in mathematics education is to provide an effective influence on practice, it must become more cumulative in nature. Single studies when linked together can push forth a coherent validation argument and have potential to build this cumulative knowledge for scholarship in mathematics education. The chapter also presents an overview of the key concepts discussed in this book.