| 1870 | Legislation establishes Agricultural College of Colorado under the Morrill Act |
| 1877 | State Board of Agriculture established |
| 1879 | Colorado Agricultural College opens |
| 1880 | Reading room established in Main Building |
| 1880 (approximate) | First librarian authorized (possibly Lillian Stroud) |
| 1887 | Lerah Stratton appointed librarian |
| 1890 | Library expands into a second room |
| 1892 | May Southworth appointed librarian |
| 1892 | Anna Jones bequest to the library |
| 1894 | Marguerite "Daisy" Stratton appointed librarian |
| 1901 | Death of Daisy Stratton; Joseph Daniels, first professional librarian, hired |
| 1903 | Federal depository collection established |
| 1904 | Library moves from Old Main to the Commercial Building |
| 1906 | Charlotte Baker hired as assistant librarian |
| 1909 | Baker replaces Daniels as library director |
| 1915 | Structural addition increases library space |
| 1917-1918 | Llibrary involved in war effort |
| 1918 | Summer library school initiated |
| 1924 | Library occupies entire Commercial Building |
| 1925-1926 | Library stacks closed to students |
| 1928 | "Oval" library opens |
| 1932 | Summer library school discontinued |
| 1933 | Library begins employing workers under New Deal programs |
| 1934 | Bibliographic Center for Research opens in Denver |
| 1936 | James Hodgson succeeds Baker as library director |
| 1938 | Library damaged in flood |
| 1940 | First branch library, Veterinary Medicine, opens |
| 1941 | Library acquires its 100,000th volume |
| 1941-1945 | Library involved in war effort |
| 1948 | Industrial Research Building used for remote storage of library materials |
| 1949 | School librarian certification program begins |
| 1951 | Second flood damages library |
| 1957 | “Bucks for Books” fund drive initiated |
| 1957 | LeMoyne W. Anderson succeeds Hodgson as library director |
| 1959 | North Central Association criticizes library |
| 1960 (approximate) | Library acquires its 200,000th volume |
| 1960-1961 | Closed-stack system ends |
| 1962-1963 | North Central Association again critical of library |
| 1963 | School librarian certification program discontinued |
| 1965 | William E. Morgan Library opens; branch libraries and remote storage discontinued |
| 1969 | "Forward CSU" fund drive initiated |
| 1974-1975 | Branch library system reinstituted |
| 1975 | Harmony Street warehouse opens |
| 1975 | Library admitted to Association of Research Libraries |
| 1976 | Library acquires its 1,000,000th volume |
| 1976 | Library joins the Ohio College Library Center, initiating the computer era |
| 1977 | Online computerized subject searching begins |
| 1979 | Library joins Research Libraries Group |
| 1980 | Separate government documents reference desk established |
| 1983 | Fourth floor built in Morgan Library |
| 1985 | InfoTrac computer system acquired |
| 1985 | Lake Street storage facility opens |
| 1985 | Joan Chambers succeeds Anderson as library director |
| 1988 | First subject oriented CD-ROMs acquired |
| 1988 | CAM online catalog becomes available |
| 1990 | Anheuser-Busch Current Periodicals Room opens |
| 1990 | CARL online catalog replaces CAM |
| 1992 | Episode of sick-building syndrome |
| 1994 | Printed card catalog removed |
| 1994 | State Legislature authorizes addition to Morgan Library |
| 1995 | Joan Chambers announces she is stepping down as dean |
| 1995 | Construction of addition begins |
| 1997 | Web version of SAGE online catalog becomes available |
| 1997 | Camila Alire appointed library dean |
| 1997 | Flash flood inundates over 400,000 volumes in library basement |
| 1998 | Addition to Morgan Library opens |
| 2001 | Alire resigns as library dean; Julie Wessling appointed interim dean |
| 2002 | SFX aggregator database enabled |
| 2003 2008 |
Catherine Murray-Rust assumes deanship Murray-Rust resigns as library dean; Patrick Burns appointed interim dean |