This chapter discusses an extended deductive database prototype system, Q-Data, developed by Bellcore to improve data quality through data validation and cleanup. The key technology component of Q-Data is the extended deductive database system LDL++, developed at MCC. We discuss the issues of data quality improvement, the relevance of the deductive database technology such as the LDL++ system to data quality improvement tasks, and the system architecture of the prototype. Furthermore, we describe our experiences using the deductive database technology in an on-going Q-Data trial attacking a real-world problem with test data from operational systems. Experiences related to engineering aspects of both the deductive database system and other component technologies, as well as pragmatic aspects of the implementation of Q-Data as a distributed system, are discussed.