The move toward commercialization and privatization has pressured airports to become more productive and competitive. Airport managers around the globe are using several performance measures to monitor their businesses and improve operational efficiency. In recent years, several studies have devised an overall productivity measure. A new study contributes to those publications in two major ways. First, unlike past studies, it explicitly considers the joint production of both desirable and undesirable outputs, that is, delays. Second, it investigates the robustness of the assessment. The results indicate that the selection of inputs and desirable and undesirable output measures can dramatically affect the productivity assessment of airports, the calculated level of inefficiency, the calculation of potential output, and the determination of productivity growth.