This book examines the issues of misclassification in epidemiology. It includes some solutions to the old and new issues of misclassification in a variety of epidemiologic design studies. The book is separated into five parts: Part I focuses on the misclassification in cross-sectional studies. Part II concentrates on the misclassification in cohort studies. Part III investigates the misclassification in case-control studies. Part IV covers hypothesis testing of no misclassification. Part V addresses the misclassification in contingency tables. It could serve as a textbook for advanced undergraduate/graduate students in medical school or students majoring in the statistics department. It could also be used as a reference book for anyone interested in the research of misclassification in epidemiologic studies.