This course helps prepare doctoral students to design research that contributes to both theory and practice. The course is organized around three key types of validity (internal, measurement, and external) that are critical to conducting high quality research, regardless of research method. Topics include middle-range theory, linking theory and data, measuring theoretical constructs, the logic of causal analysis, model specification, field experimentation, multiple indicator models, and sample selection bias. One goal of the course is to give students insight into the challenges researchers face as they apply social science theory to real-world problems and settings. Another goal is to introduce students to a range of options for meeting these challenges.