This paper describes the impact that technological change over the past few decades has had on a number of key interfaces to the library catalog, including the user, resource, abstract/index, and union catalog interfaces. Areas of focus for future development are then highlighted, including: (1) reassessing data requirements and conventions in order to ensure that the data recorded in the catalog is adaptable to the description of those resources and that it is adequate to support the various applications that will draw on it; (2) re-examining the interfaces to ensure that the requirements and interdependencies are fully understood; and (3) repositioning the catalog to meet the needs of its users. (MES)