This book provides a comprehensive introduction to the principles and practice of designing public health studies, with a focus on both observational and experimental designs commonly used in biomedical and population-based research. Drawing from years of teaching the "Design of Public Health Studies" course at UNC, the book bridges theory and application to help readers understand, plan, and critically evaluate health research. Key study designs discussed include cross-sectional, case-control, cohort, and clinical trials, with in-depth treatment of core concepts such as validity, response measurement, sample size determination, matching, and randomization.The book is intended for graduate students, researchers, and public health professionals with foundational training in statistical methods (e.g., undergraduate-level Principles of Experimental Analysis or Basic Elements of Probability and Statistical Inference), especially those familiar with software like R or SAS. It will also be valuable to informed readers seeking to interpret health research critically.By emphasizing practical understanding and real-world relevance, this book equips readers with the skills needed to design strong studies, assess the methodological rigor of published research, and communicate statistical findings effectively in public health contexts.