This textbook was born from a disparate collection of written materials that were created to teach Epidemiology and Biostatistics to second year medical students at the University of Washington. These materials included handouts, practice problems, guides to reading research articles, quizzes, notes from student help sessions, and student emails. The primary goal of these written materials, and now this book, is to recreate the perspective of learning Epidemiology and Biostatistics for the first time. With critical editing assistance from Epidemiology faculty, graduate students in Epidemiology and Biostatistics, and the students themselves, I have tried to preserve the innate logic and connectedness of clinical research methods and to demonstrate their application. The textbook is designed to provide students with the tools necessary to form their own informed conclusions from the clinical research literature. More than ever, a clear understanding of the fundamental aspects of Epidemiology and Biostatistics is needed to successfully navigate the increasingly complex methods utilized by modern clinical research studies. This book could not have been created without the dedicated help of the e- tors, the teaching assistants, and the students, who asked the important questions. I would especially like to thank my family who patiently allowed me so much time to write.