Usability is integral to software quality. Software developers increasingly acknowledge the importance of user-centered Web-site development. The value of usability engineering and the role of the usability engineer (UE) are less well understood. A common assumption is that the UE’s role is only to be a user advocate. To this role, we add the responsibility of addressing concerns of other stakeholders in Web-site design and development. We discuss usability engineering and the processes that it encompasses, such as project planning, requirements-definition, user-centered design and evaluation/testing within the context of traditional software engineering lifecycles. We define the UE’s role throughout a user-centered Web-site development lifecycle. This lifecycle integrates compatible usability engineering processes into software engineering processes, drawing examples from research and experience.