This is a course in applied econometrics organized around the contemporary design-based approach to empirical research in the social sciences. The course is guided by the question, "What can you credibly say about the results of econometric research?" We will study the assumptions underlying regression and common research designs, the errors researchers make in interpreting their findings, and how a study's research design itself determines what kinds of claims it can support. Students will learn to interpret empirical results in light of economic theory, including weighing alternative explanations for those results. In weekly labs, students will work with real-world data to build skills in statistical software and good habits for replicable research that will serve them well in the workplace or in further graduate study. Throughout, the course takes a critical approach to these methods, paying attention to their limits as well as their potential uses for policy evaluation and analysis.