How to access and search using the Online Library System (OLS) is described. The OLS is a computerized list of bibliographic citations compiled by the library network of the Environmental Protection Agency (EPA). It consists of several related databases and can be used by anyone to search for books, documents, journals, and other materials. In addition to the national catalog, materials on hazardous wastes, clean lakes, EPA Region 1, and the chemical collection system are included. The menu-driven user-friendly system is available at no cost other than telecommunications charges to support public access to environmental information. Chapters cover the following topics: (1) starting the system; (2) selecting a database; (3) setting parameters; (4) the patron menu; (5) search options; (6) other options; and (7) printing from the OLS. An appendix lists stopwords used in indexing databases. A list of EPA libraries is included. (SLD)