This report describes the RAND Metadata Management System (RMMS), a system that manages metadata--definitional and descriptional information about databases, simulation models, and procedures--for relational databases such as those maintained in INGRES. Many of these databases have little documentation or other descriptional information to accompany them, making it difficult for users to understand the definitions, abbreviations, acronyms, and descriptions of the data elements stored and maintained in a database management system. The authors developed the RMMS with five major goals in mind: (1) provide complete, thorough, and standard database documentation; (2) record and manage information about different versions of each database; (3) maintain a history of the changes made to database tables, schema, or data values; (4) facilitate deriving databases for input to simulation models and for sharing among models; and (5) standardize the names of data elements that are conceptually the same but named differently or are named the same but are conceptually different. This report should be of help to users of other relational databases who would like to develop a similar metadata repository for their own set of databases.