Subject classifications and thesauri have become more important than ever in the Web environment. Efforts made to organize information into subject classifications, or taxonomies, offer users the opportunity to substantially improve the effectiveness of their search and retrieval activities. This article continues earlier research on the development of a new definition of the field of information science and the creation of a "map" of the field showing subjects central to it and their relationships to those on the periphery. A case study describes the creation of a new classification structure (taxonomy) for the Information Science Abstracts (ISA) database, aiming to reflect and accommodate the rapid and continued technological and market changes affecting the information industry today and into the future. Based on a sample of some 3,000 ISA abstracts, two validation experiments were conducted by a three-member team comprising a database editor, a reference librarian, and an abstractor-indexer, who represent three of the major communities within the information science field. In the first experiment, the sample of abstracts was classified according to the proposed new taxonomy; after analysis of the data and revision of the taxonomy, it was revalidated and fine tuned in a second experiment. Indexer consistency measures obtained in this study were significantly higher than those found in previous studies. The taxonomy resulting from this research employs the concepts, definition, and map of information science previously developed. It presents them in an organized hierarchical view of the field and thus makes a significant contribution to information science.
