This paper compares and contrasts relational data base management systems (RDBMSs) and frame knowledge representation systems (FRSs). We compare the capabilities that RDBMSs and FRSs provide to designers and users of computer information systems. We consider capabilities at three different levels: symbol-level capabilities such as storage capacity, persistence, and shared use; system-engineering level capabilities such as run-time schema alteration, design guidelines for schema organization, inheritance, and classification; and knowledge-level capabilities such as expressive power and inference. No previous publication considers the full range of differences between these systems that are presented here. We also consider the factors that have shaped the current differences between RESs and RDBMSs, and present trends in the continuing evolution of these systems. FRSs are in danger of extinction should their architects not provide them with certain symbol-level DBMS capabilities.