This concise, user-friendly book provides an accessible guide for anyone wishing to pursue an epidemiological study. It provides the essential tools to understand what epidemiology is, how to choose the correct observational study design for a research question, and how to collect or access data to conduct the study. The book begins by considering, in light of the COVID-19 pandemic, the importance of epidemiological studies, as well as highlighting key issues such as bias, causality, and ethics. There are then chapters on the different types of observational epidemiological studies, including case studies, ecological and mixed methods, and the data sources available to researchers. Following this, and central to the book, is a step-by-step case study on how to conduct a cross-sectional project. Concluding by guiding readers from conducting the research to publishing its findings, this is the ideal companion for students, researchers, or healthcare professionals approaching epidemiological research for the first time.