Computational modeling holds significant promise as a tool for improving how theory is developed, expressed, and used to inform empirical research and evaluation efforts. However, the knowledge and skillsets needed to build computational models are rarely developed in the training received by social and organizational scientists. The purpose of this manuscript is to provide an accessible introduction to and reference for building computational models to represent theory. We first discuss important principles and recommendations for “thinking about” theory and developing explanatory accounts in ways that facilitate translating their core assumptions, specifications, and ideas into a computational model. Next, we address some frequently asked questions related to building computational models that introduce several fundamental tasks/concepts involved in building models to represent theory and demonstrate how they can be implemented in the R programming language to produce executable model code. The accompanying supplemental materials describes additional considerations relevant to building and using computational models, provides multiple examples of complete computational model code written in R, and an interactive application offering guided practice on key model-building tasks/concepts in R.