This book provides a practitioner's foundation for the process of explanatory model building, breaking down that process into five stages. Donald W. Katzner presents a concrete example with unquantified variable values to show how the five-stage procedure works. He describes what is involved in explanatory model building for those interested in this practice, while simultaneously providing a guide for those actually engaged in it. The combination of Katzner's focus on modeling and on mathematics, along with his focus on the explanatory performance of modeling, promises to become an important contribution to the field.