This case report describes the design of a comparative health study using secondary analysis of population-based data. The study was designed to understand how proximal (i.e., educational level, income level, partnership status, and race) and distal (i.e., social policy context) risk factors affect the health of mothers of young children. Using the author’s own experience, three fundamental steps to designing a comparative study are discussed: (1) selecting the data source, (2) selecting the outcome and associated risk variables, and (3) selecting an analytic method. Limitations of this type of research design are mentioned, including heterogeneity in the composition of groups being compared and the difficulty isolating the effects of a particular distal factor. Take-away messages for the readers undertaking a comparative health study include the need to carefully consider the selection of a data source, the benefit of having a clear conceptual model and research questions to guide design decisions, and the usefulness of sensitivity analyses to test the robustness of the findings. Overall, a comparative research design is recommended by the author, especially when its limitations are known up front, because of its unique ability to capture natural differences at a contextual level that would not be possible in an experimental setting.