Companies can use information technology not only to conduct transactions with their customers but also to provide them with valuable functionalities before, during, and after those transactions, such as recommen- dations on what products to buy or to track product delivery. The e-Business environment provides a particu- larly fertile ground for leveraging IT resources to provide functionality. Although the general perceptions of online service quality and self-service technologies have been extensively studied, there has not yet been a through investigation into the specific functionality that IT can provide for delivering services that supplement a core product offering. This paper examines the role of IT as a service delivery mechanism. Drawing on a customer service life cycle framework and the concept of supplementary service, we propose and operationalize the construct of functionality: the broad array of IT applications that can enhance a customer’s experience with a company beyond just the core offering. Functionality focuses on specific IT-based service tools as opposed to broad perceptions of service (e.g., service quality) and so targets a key IT artifact. A cross- sectional survey of current e-Business customers was used to validate the multidimensional functionality construct as well as to test a theoretical model relating functionality to the consequences of satisfaction, perceived website usefulness, and continued website usage. The results support that functionality is not only a conceptually valid construct but also one that is highly regarded by e-Business customers.