In a recent issue of Industrial Marketing Management, Johnston, Leach, and Liu made a strong case for the use of case studies. Although they convincingly argued that researchers should follow a rigorous and systematic approach in conducting case studies, they failed to address the most important criticism of case studies, i.e., their alleged lack of generalizability. In this reaction to their article, the extent and nature of case studies' generalizability in theory-testing is discussed. For this purpose, the concept of theoretical generalization is presented and defined, and it is argued that in publishing the findings of their case studies, researchers need to demonstrate the existence of causal relationships along with their results.