The SRTC, according to its mission in promoting the statistical knowledge of society, has put the writing and publication of specialized books and magazines on its agenda. The authorship of the present book is one of the measures that have been taken by SRTC to implement this policy, and it is hoped that it will be useful for researchers and students in the field of statistics and related fields. The analysis of cross-sectional and longitudinal classified data in the fields of official statistics, social sciences, and medicine has evolved dramatically in recent decades. The book Discrete Multivariate Analysis in Cross-sectional and Longitudinal Studies has modeled and analyzed classified data that contains applications in social, economic, and medical issues and can be used for decision-makers in the country's statistical system. Considering the large quantity of classified data in cross-sectional and longitudinal studies in the statistical system of the country, it is obvious that their analysis and modeling can have a major impact on the production of statistical knowledge in general and wide applications in the statistical system in particular. Currently, in the scientific community of the country, the lack of books related to this topic is quite obvious. The publication of the present book can partially fill the existing gap and, especially in terms of its pivotal feature as a textbook, can be effective in publishing and disseminating statistical knowledge centered on "discrete multivariate analysis". The present book has been authored by Dr. Ganjali and Dr. Rezaei Ghahroudi, which is based on the long experience of teaching and supervising several dissertations in this field in universities, which hereby these loved one's efforts are appreciated and thanked. This book has been edited by Mr. Farshid Khanzadeh and judged by Dr. Abbas Gerami, thus we thank and appreciate the efforts of these loved ones, also. All readers and respected experts are requested to help us achieve our desired scientific goals by submitting their opinions.