Maintaining the quality of data resources has been a continuing concern for information systems professionals. Over time techniques have been developed for maintaining the appropriate level of quality for individual databases, for data warehouses and for transaction processing systems. However, web-based systems lack the tools and procedures for data quality to be properly maintained. My dissertation seeks to develop methods that can be used to improve web-based data quality. It maps data quality dimensions, as identified in prior research [Wand et. al., 1996, and Wang et. al., 1995], to the web domain and then proposes methods that can help maintain each of these data quality dimensions.