In recent decades, the science of reading acquisition has been advancing through interdisciplinary research in cognitive, psycholinguistic, developmental, genetic, neuroscience, cross-language, and experimental comparison studies of effective instruction. Some of the science of reading has emerged from the theory and research into the realm of practice and policy. Yet the science and practice of measuring “reading comprehension” has remained relatively immune to much of this foundational knowledge. Measuring Up questions the traditional format of reading comprehension tests, typically a single series of questions asked about a series of passages, and offers ideas and innovations we might expect in a next generation of 21st century reading assessments. Sabatini, Albro, and O'Reilly believe that in light of the move towards Common Core State Standards and assessments, as well as significant national investments in reading and literacy education, it is a critical and opportune time to bring together the research and measurement community to address fundamental issues of measuring reading comprehension, both in theory and in practice.