This paper traces the development of classification at the Library of Congress in terms of its broader context and by accounting for changes in the present system since its initial period of creation between 1898 and 1910 and the present. Topics covered include: (1) Early Growth of the Collections; (2) Subject Access During the Early Years; (3) A. R. Spofford and the Growth of the Library of Congress; (4) Spofford and Subject Access; (5) From Spofford to John Russell Young; (6) Trends in Classification; (7) A Tentative Beginning, 1897-98; (8) Years of Decision, 1899-1901; (9) Classification Development, 1901-11: General Features; (10) Classification Development, 1901-11: Collocation Patterns; (11) Progress on the Classification: 1901-11; (12) Classification Development: 1912-30; (13) Classification Development: 1930-46--An Interlude; and (14) Classification Development: 1947-Present. A list of annotated references completes the report. (THC)