Most psychological theories are "verbal models": narrative explanations of a psychological phenomenon. Because of the vagaries of language, these theories are vulnerable to hidden assumptions and shortcomings. Moreover, they create fertile ground for questionable research practices. In this workshop, we provide an introduction to theory development through computational modeling. First, we review the advantages of modeling and show how it fosters transparent and cumulative science. We then propose ideas for how to develop and evaluate formalized theories. We provide examples throughout, focusing especially on a computational model of Panic Disorder. Our hope is that participants leave with an appreciation of the importance of formalized psychological theories and ideas for how to develop and evaluate formalized theories in their own work. We will illustrate the process of generating a computational model in R using difference equations. Although prior knowledge in these areas is not necessary to understand the main points of the workshop, it would likely facilitate understanding for parts of the workshop. Importantly, this is not a workshops were we will work hands-on in R, so no laptops are required.