Internet and World-Wide Web have transformed how we communicate and conduct business. Increasingly, business customers are using the web to manage their day-to-day operations and to obtain support for the products they purchase. Electronic support tools using the Internet have enhanced support providers' capabilities and at the same time enable users to become self-sufficient. Although telephone-based service remains the most prevalent support medium today, the Internet is the fastest growing medium, and future users are more likely to turn to the Internet for their product support needs. Web-based support offers great opportunities for firms: I) to reduce the cost of delivering support, 2) to improve the quality of support provided, and 3) to use technology as a key competitive differentiation in their support services. However, industry studies indicate that some firms are not satisfied with web-based support systems, which in these cases has prevented web-based systems from becoming the preferred medium for obtaining support.((1)) This paper is concerned with identifying the critical factors affecting the use of a web-based self-support system at the Hewlett-Packard Company. Hewlett-Packard business customers have the ability to obtain a wide range of support services using HP's web-based support system, the Electronic Support Center (ESC). The exploratory phase of this study was conducted through a review of the published literature concerned with web-based self-support systems. Focus group studies herd at Hewlett-Packard identified some factors that were considered to be important. As a result of both the literature survey and the focus group studies, the effective factors were classified into four groups: 1) operational effectiveness of the ESC (availability and performance), 2) functionality (feature sets), 3) usability (customer experience), and 4) customer demographics (type, size, and location). Hewlett-Packard's support customers were randomly surveyed over a 46 month period to determine how these factors influence their desire to use the ESC as the primary medium to obtain support. Results of the HP customer survey were analyzed quantitatively and qualitatively to arrive at the critical factors determining the use of the ESC. Analysis of this data shows that users were generally satisfied with the ESC. Availability and performance were the most significant factors. Improvements in Knowledge Search and Patch Digests contribute the most to increasing user satisfaction. Users also call for a tighter system integration of the HP ESC and telephone-based Response Center.