- Community Service Society of New York. Committee on Family and Child Welfare1
- Community Service Society of New York. Department of Public Affairs1
- Comstock, J. L. 1789-18581
- Comstock, Sarah1
- Conant, Charles A. 1861-19151
- Conference House Association (Staten Island, New York, N.Y.)1
- Conference for the Study of the Negro Problems Atlanta University) 19121
- Congdon, Charles T. 1821-18911
- Connecticut. State Highway Department2
- Connors, Chuck, 1921-19921
- Conrad, Ephraim, 1769?-18341
- Conservation of Human Resources Project (Columbia University)1
- Consolidated Telegraph and Electrical Subway Company1
- Continental Insurance Company1
- Converse, Harriet Maxwell, 1836-19031
- Cook, Harry T. 1873-1
- Cook, Joel, 1842-19101
- Cooke, Jean G1
- Cooper Square Community Development Committee and Businessmen's Association1
- Cooper Union Museum for the Arts of Decoration1
- Cooper Union for the Advancement of Science and Art2
- Cooperative Press1
- Cornell, William Mason, 1802-18951
- Corradini, Robert Everett, 1891-2
- Corthell, E. L. 1840-19161
- Cory, Florence Elizabeth1
- Costello, Augustine E2
- Cotter, Oliver1
- Couch, J. P1
- Country Life Press2
- Courdert, Frederick René1
- Courtin, F1
- Couzens, M. K1
- Covello, Leonard, 1887-19821
- Cowan, John F1
- Cox, Samuel Sullivan, 1824-18891
- Cozzens, Issachar, 1780-18651
- Craighead, Robert1
- Cram, Ralph Adams, 1863-19421
- Crandall, Charles H. 1858-19231
- Crane, Stephen, 1871-19002
- Crawford, Morris D., Jr., 1915-19991
- Crisp, Arthur, 1881-19741
- Crockett, Davy, 1786-18361
- Crommelin, Edward1
- Cronkite, Walter1
- Croome, William, 1790-18601
- Crosby, Howard, 1826-18911
- Crosby, James L1
- Crosby, Oscar Terry, 1861-19471
- Crosby, William O. 1850-19251
- Croscup, George E. 1851-19171
- Cross & Brown Company1
- Croswell & Van Benthuysen1
- Croswell, Edwin, 1797-18711
- Crown Publishers1
- Crowninshield, Frank, 1872-19471
- Cruikshank, George, 1792-18781
- Crystal Spring Water Company1
- Cui, Guoyin, 1831-19091