DATA PRESENTED IN THIS REPORT WERE BASED PRIMARILY ON QUESTIONNAIRE RESPONSES OBTAINED THROUGH A NATIONAL CENSUS OF SPECIAL LIBRARIES AND INFORMATION CENTERS. THE SURVEY WAS MADE DURING THE PERIOD FROM AUGUST 1961 TO FEBRUARY 1963. ALTHOUGH THERE WERE MORE THAN 10,000 ENTRIES IN THE PUBLISHED DIRECTORY, EXCLUSION OF CANADIAN LIBRARIES AND DELETION OF A NUMBER OF QUESTIONABLE ENTRIES REDUCED THE TOTAL TO 8,533. THROUGH A SERIES OF 23 TABLES, LIBRARY DATA ARE PRESENTED IN TERMS OF NUMBER, INSTITUTIONAL SETTING, MAIN SUBJECT INTEREST, SIZE AND COMPOSITION OF STAFF, VOLUME HOLDINGS, PERIODICAL SUBSCRIPTIONS, DATES OF ESTABLISHMENT, AND GEOGRAPHICAL DISTRIBUTION BY STATE AND METROPOLITAN CENTER. THE FIVE MAJOR ORGANIZATIONAL CATEGORIES ARE--(1) COLLEGES AND UNIVERSITIES, (2) COMMERCIAL AND INDUSTRIAL FIRMS, (3) GOVERNMENT AGENCIES, (4) PUBLIC LIBRARIES, AND (5) OTHER ORGANIZATIONS. (JC)