When performance assurance is not included in the software development process, the poor performance of resulting applications will create strong interest in the subject and motivation to change the process to address the problem. In spite of this strong interest, however, such a change in the process can be more difficult than expected. Based on our experience in adding performance assurance to a software development process that did not include it, we present guidelines for establishing performance assurance in an environment of large-scale application development. In our environment, a centralized organization was responsible for computing facilities, and user organizations were responsible for application development. Finally, the management infrastructure and support needed for effective performance assurance is described.