The response time of a WWW service often plays an important role in its success or demise. From a user's perspective, the response time is the time elapsed from when a request is initiated at a client to the time that the response is fully loaded by the client. In this talk, I will present a framework for accurately measuring the client-perceived response time in a WWW service. Our framework provides feedback to the service provider and eliminates the uncertainties that are common in existing methods. This feedback can be used to determine whether performance expectations are met, and whether additional resources (e.g. more powerful server or better network connection) are needed. The framework can also be used when a consolidator provides Web hosting service, in which case the framework provides quantitative measures to verify the consolidator's compliance to a specified Service Level Agreement. Our approach assumes the existing infrastructure of the Internet with its current technologies and protocols. No modification is necessary to existing browsers or servers, and we accommodate intermediate proxies that cache documents. The only requirement is to instrument the documents to be measured, which can be done automatically using a tool we provide. I will also discuss actual response time data we have obtained from instrumenting "The Wondering Minstrels", a poem-of-the-day web site served out of Rice University.