The work in this thesis is at the intersection of two historically distinct research areas, namely Information Retrieval/Filtering and Software Agents. Information Retrieval is a well established field of information science that addresses issues of retrieval from a large collection of documents in response to user queries. Information Retrieval literature has recently begun to address issues of Information Filtering [13][11][7]. By comparison, Agent research is a relatively new field of study which has grown out of Artificial Intelligence (AI). Agent research is concerned with issues of designing intelligent and autonomous software for a variety of tasks. This thesis draws upon work from both these areas.