This entry considers initially the different types of research studies that can be carried out in educational research, and their relationship to cross-sectional studies, the advantages and disadvantages of cross-sectional studies, the usefulness of cross- sectional studies, the difference kinds of research studies that are essentially cross-sectional in nature, as well as the gradations in types of investigation between cross- sectional and longitudinal research studies. In addition, this entry discusses issues concerned with the design of a cross- sectional study, the role of sampling, the methods of data collection, the value of pretest and pilot studies, and the major sources of error in such studies. A further important issue, which is addressed, involves the analysis of data and the problems of explanation associated with the relationships reported from cross-sectional studies in contrast to longitudinal and experimental studies.