The conversion from the Dewey Decimal Classification to the Library of Congress Classification in academic libraries, 1955 to 1975

The conversion from the Dewey Decimal Classification System (DDC) to Library of Congress Classification (LC) in academic libraries from the 1950s to the 1970s was one of the most abrupt and expensive changes in library history. This study examines the reasons for this change through a multimethodological approach.;Questionnaires sent to 333 systematically selected LC libraries showed that among libraries that converted to LC, 44% initiated the conversion during the years 1965 to 1969. Conversion was made for a variety of reasons, including alleged cost effectiveness (26% of responses), specificity of LC (18% of responses), and inter-library standardization (12% of responses). Strong relationships between collection size and specificity of classification and between collection size and intra-library standardization were indicated. Further strong relationships were indicated between year of conversion and both automation and intra-library standardization. From questionnaires sent to 150 DDC libraries, 59% of the responses indicated reasons of cost for not changing to LC.;Professional literature of the period, 1955-1975, suggests that the conversion was done with little planning or study with regard to potential costs. Few cost studies were done and some of those that were done were primarily inhouse and remain unpublished. Furthermore, other arguments to convert or not were often not based on empirical research or verifiable data.;Analysis of the papers of prominent consultant and LC advocate, Maurice Tauber, revealed, for the most part, that he advocated that academic libraries regardless of size and resources convert to LC. Questionnaires indicated, however, that consultants played only a minor role (5% of responses) in the decision to convert.;Reviews of the annual reports of the Library of Congress indicate a distinct drop in the classification of titles in DDC from 1955 to 1966 compared to the previous twenty-five years, while LC classed titles increased. The period of decline in the number of titles classed in DDC as a percentage of titles classed in LC roughly matches the onset of large scale conversion to LC in academic libraries.