Historically, discrete-event process simulation was used first and most often to the study and benefit of manufacturing processes. Its domains of use have steadily expanded during approximately the last half-century to include supply chain operations, computer networks, health care, and retail service. All of these economic domains exhibit intense competitiveness. The application of simulation presented in this paper involves a local, traditional grocery store facing competitive pressure from an encroaching “big-box” chain store. As a countermeasure, management wished to assess potential investment in a self-checkout system to supplement staffed checkout lanes. An analysis using discrete-event process simulation greatly aided this assessment of the ability of self-checkout lanes to improve customer service by reducing wait times.