A fundamental of the Space Station Freedom Program (SSFP) is cooperation of International Partners in the development of an on-orbit laboratory facility. The United States, Japan, and Europe will each provide a laboratory of their own design that can be used by all of the participants. The common unit within each module for experimentation is the the International Standard Payload Rack (ISPR). While the rack must provide sufficient flexibility to be useful to the scientific user, it must also provide standardized interfaces for installation and functionality within each partner's laboratory. This paper will focus on the development of the ISPR and its interface and system requirements.