The University Archives' staff has compiled summaries from sources in the Archives about athletic conference membership at Case Institute of Technology, Western Reserve University and Case Western Reserve University from 1902 through 2020.

Western Reserve University
10/1902-5/1932: Ohio Athletic Conference (OAC)
2/1946-6/1955: Mid-American Conference (MAC)
9/1955-1969/72: Presidents' Athletic Conference (PAC)*

Case Institute of Technology
10/1902-9/1948: Ohio Athletic Conference (OAC)
7/1955-1969/72: Presidents' Athletic Conference (PAC)*

Case Western Reserve University
1969/72-6/1984: Presidents' Athletic Conference (PAC)*
9/1984-6/1999: North Coast Athletic Conference (NCAC)
9/1987-current (as of 2019/20): University Athletic Association (UAA)
2014-current (as of 2019/20): associate member of President's Athletic Conference for football

*Case Institute of Technology and Western Reserve University federated on July 1, 1967 to create Case Western Reserve University. Despite federation, Case and WRU maintained separate varsity teams. As each sport merged between 1969 and 1972, separate Case and WRU memberships were replaced by a single CWRU membership.

Sources:
19TD 4:5 Report, ?, "Brief History of Membership of the Ohio Athletic Conference," undated
21PN1 7:3 ?, "A Common Footing," The Adelbert (November 1902): 55
4PN1 7:1 Dick Grottron, "Reserve Out of Big Six Track Meet," The Reserve Weekly (5/24/1932): 1, 8
4PN2 2:5 Fred Livingtone, "Midwest Conference Meets in Columbus," The Reserve Tribune (3/21/1946): 5
1DB8 2:5 Chuck Heaton, "Reserve Plans to Play Old Big Four Rivals," Cleveland Plain-Dealer (2/25/1946)
20JA 5:1 Case Alumnus (August 1948): 77-78
20PN1 8:3 ?, "Ohio Conference Weakened as Case, Others Withdraw," Case Tech (9/24/1948): 4
1DB9 11:7 Letter, Alfred J. Hotz to Dean Harshman, 5/11/1954
21TF 4:5 Report, ?, Football File for Press/Radio/TV, 1954
1DB9 11:7 Constitution, Presidents' Athletic Conference, 12/17/1954
21TF 4:5 Report, Art Rosenberg, 1955 Football Brochure, 1955
1DB11 18:7 Letter, Robert Morse to Presidents' Athletic Conference Presidents, 12/19/1967
1DB11 18:7 Report, ?, Notes from Athletic Directors' Council meetings, November 8-9, 1970, 11/16/1970
1DB11 18:7 Letter, Louis Toepfer to Presidents' Athletic Conference Presidents, 1/4/1971
7PR 9:1 Press Release, Office of Public Information, 1/6/1971
6DB3 73:9 Letter, David Ragone to Howard J. Burnett, 2/18/1983
6DB3 73:9 Press Release, ?, 2/1983
2N 3:2 Minutes, CWRU Board of Trustees, 3/21/1983
6DB3 73:9 Memorandum, David Ragone to Peter Musselman, 3/31/1983
2N 4:1 Minutes, CWRU Board of Trustees Executive Committee, 4/15/1986
6DB3 73:11 Minutes, University Athletic Association, 6/4/1986