This study reports and compares patron usage rates from January 1987 to May 1988 for three separate ERIC database systems at the library at Texas Woman's University (TWU): (1) online searches of the ERIC file through the mainframe computers of DIALOG Information Services (DIALOG ERIC), which are offered in the library reference department by trained search specialists to patrons for a fee; (2) TWU-ERIC, an online system based on the university mainframe computer, which is offered to patrons to perform their own searches without a fee; and (3) SilverPlatter ERIC, a laser-based CD-ROM version of the ERIC file (CD-ROM ERIC), which is also provided to patrons to perform their own searches without a fee. A table displays statistics describing the usage rates for each of the three systems. It is concluded that CD-ROM ERIC contributed significantly to a marked decline of both DIALOG ERIC and TWU-ERIC searches because patrons preferred cost-free searching, user-friendly search software, and accessibility to search equipment. Analyses of the costs of the three systems indicate that CD-ROM ERIC, as well as being the system preferred by most users and staff, is also the least expensive to provide. (CGD)