The incorporation of rules in database systems has been an important area of database research for more than a decade. It plays a major role in the integration of behavioural information and the structural data with which commercial databases have traditionally been associated. This integration can lead to a more straightforward application development and also to more efficient processing of data. This volume contains papers from the 1st International Workshop on Rules in Database Systems. The aims of the workshop were to examine the current state of the art, to explore relationships between different categories of rule system, and to identify complementary areas for further development. The resulting volume deals with both the theoretical and practical issues relating to rules in database systems. Recent results are reported on different aspects of and approaches to database rules including active databases, deductive databases, integrity constraints, and the integration of active and deductive technologies. Particular emphasis is given to active rules, an issue which has recently come to the forefront of database research.