This chapter covers how the model is used to actually implement a simulation design in a modeling project. In the purest sense, “execution” is the running of the model, but here, the term is used in a broader sense—running the model for all replicates in the simulation design. There are five simple steps involved in project execution: (1) understand the model to know if there is a problem, (2) find computing resources, (3) design output storage structures, (4) develop computer scripts to efficiently run the model for all scenarios, and (5) start the simulations and scripts. Major execution concerns are addressed at the end of the chapter.