This report presents statistics on the 107 university libraries and 12 independent research libraries that were members of the Association of Research Libraries (ARL) during the 1990-91 fiscal year. Data are reported in alphabetical and rank order on collections (volumes in library, gross and net volumes added, monographs purchased, current serials purchased and not purchased, microform holdings, and government documents); interlibrary loans; personnel (professional staff, non-professional staff, and student assistants); and expenditures (monographs, current serials, other library materials, miscellaneous materials, contract binding, salaries and wages, other operating expenditures, and total library expenditures). Statistics on Ph.D.s awarded, faculty, and enrollment are also provided, as well as a summary of the rank order tables of university libraries and rank order tables for each of 18 categories from the main ARL data tables. A copy of the ARL statistics questionnaire is attached. (MAB)