Although International Association for the Evaluation of Educational Achievement-pioneered international large-scale assessment (ILSA) of education is now a well-established science, non-practitioners and many users often substantially misunderstand how large-scale assessments are conducted, what questions and challenges they are designed to address, and how technologies have evolved to achieve their stated goals. This book focuses on the work of the International Association for the Evaluation of Educational Achievement (IEA), with a particular emphasis on the methodologies and technologies that IEA employs to address issues related to the validity and reliability (quality) of its data. It outlines how IEA studies are conducted, from developing the research questions to constructing study frameworks, to designing the instruments (assessment materials, background questionnaires, and manuals), establishing the important aspects when conducting a study, and reporting on the results. This book shows the rigor of these scientific endeavors and the quality control mechanisms that are required to ensure high quality data and high quality study reports. It also reveals how ILSAs in education have evolved. [For Volume 9, see ED601925.]