A methodology for the operational design of an airport limousine service is presented. The design procedure involves optimization of a total cost function (involving operating cost and passenger time) for headway and zone dimensions, given rectangular zones. Effects of using layover buffers to dampen variations in run times are considered. Route-deviation service is compared to taxi-fed, limited-stop service. An extensive sensitivity analysis on the model parameters is included, and an application of the methodology to San Francisco International Airport is briefly described.