ProQuest LLC is an Ann Arbor, Michigan-based electronic publisher and microfilm publisher. It provides archives of sources such as newspapers, periodicals, dissertations, and aggregated databases of many types. Its content is estimated at 125 billion digital pages. Content is accessed most commonly through library internet gateways, with navigation through such search platforms as ProQuest, CSA Illumina, Dialog, Datastar, Chadwyck-Healey, eLibrary and SIRS. Microfilm publishing is under the UMI brand. The current chief executive officer is Kurt Sanford. ProQuest is part of Cambridge Information Group.
Eugene Power, a 1930 M.B.A. graduate of the University of Michigan, founded the company as University Microfilms in 1938, preserving works from the British Museum on microfilm. In his autobiography Edition of One, Power details the development of the company, including how University Microfilms assisted the OSS during World War II. This work mainly involved filming maps and European newspapers so they could be shipped back and forth overseas more cheaply and discreetly.
Power also noticed a niche market in dissertations publishing. Students were often forced to publish their own works in order to finish their doctoral degree. Dissertations could be published more cheaply as microfilm than as books. ProQuest still publishes so many dissertations that its Dissertations and Theses collection (formerly called Digital Dissertations) has been declared the official U.S. off-site repository of the Library of Congress.
Xerox owned the company for a time in the 1970s and 1980s, and it was later bought by Bell & Howell. The name of the company changed several times in this period, from University Microfilms to Xerox University Microfilms, to University Microfilms International, then shortened to UMI.
In the 1980s, UMI began producing CD-ROMs that stored databases of periodicals abstracts and indexes. At a time when modem connections were slow and expensive, it was more efficient to mail database CD-ROMs regularly to subscribing libraries, who installed the discs on dedicated PCs. The ProQuest brand name was first used for databases on CD-ROM. An online service called ProQuest Direct was launched in 1995; its name was later shortened to just ProQuest. The bibliographic databases are mainly sold to schools, universities and libraries.
In 1999, the company name changed to Bell & Howell Information and Learning, and then in 2001 to ProQuest Information and Learning.
In 1998 ProQuest announced the "Digital Vault Initiative", purported to include 5.5 billion images digitized from UMI microfilm, including some of the best existing copies of major newspapers dating back 100 to 150 years, and Early English books dating back to the 15th century. While work continues to digitize the contents of the microfilm vault, ProQuest is already providing navigation of 125 billion digital pages, including nearly 20 million pages of newspaper content dating from pre-Revolutionary War America.
In 1999 ProQuest acquired Chadwyck-Healey, a one-time microfilm publishing company that was one of the first to produce full-text CD-ROM databases. This acquisition gave Proquest ownership of a 100+ person publishing operation based in Cambridge, England and became the basis for a substantial overseas expansion.
In 2001 Proquest acquired Norman Ross Publishing, a small New York based microfilm publisher. 
ProQuest Information and Learning acquired Seattle start-up Serials Solutions, a venture providing access management and search services for content hosted by other companies, in 2004.
In 2004 ProQuest Information and Learning acquired Copley Publishing Group.
ProQuest Company, then the parent company of ProQuest Information and Learning, sold it to Cambridge Information Group in 2006. ProQuest Information and Learning was merged with CSA in 2007 to form ProQuest CSA. Later that year it was renamed ProQuest LLC.
In 2008, ProQuest acquired complete ownership of RefWorks, a web-based citation manager of which it had been part owner since 2001. RefWorks was merged with ProQuest's existing COS business to form RefWorks/COS. Also in 2008, ProQuest acquired Dialog, a major online database firm, from Thomson Reuters.
In 2010, ProQuest acquired two properties from LexisNexis, Congressional Information Service (CIS) and University Publications of America (UPA). CIS includes one of the world's most exhaustive online collections of legislative content and highly respected statistical works, while UPA includes deep historical sets. The acquisition includes digital products and an expansive microfilm vault that will be energized through ProQuest's strength in conversion from film to searchable electronic formats.
- The American Hebrew & Jewish Messenger (1857–1922)
- The American Israelite (1854–2000)
- The Arizona Republic (1890–1922)
- Atlanta Daily World (1931–2003)
- Atlanta Journal-Constitution (1868–1945)
- The Baltimore Afro-American (1893–1988)
- The Baltimore Sun (1837–1988)
- The Boston Globe (1872–1982)
- Chicago Defender (1910–1975)
- Chicago Tribune (1849–1990)
- Christian Science Monitor (1908–2000)
- The Cincinnati Enquirer (1841–1922)
- Cleveland Call & Post (1934–1991)
- Detroit Free Press (1831–1922)
- The Globe and Mail (1844–2010)
- The Guardian (1821–2003) and The Observer (1791–2003)
- Hartford Courant (1764–1988)
- Indianapolis Star (1903–1922)
- Irish Times (1859–2012) and The Weekly Irish Times (1876–1958)
- Jerusalem Post (1932–1988)
- The Jewish Advocate (1905–1990)
- Jewish Exponent (1887–1990)
- Los Angeles Sentinel (1934–2005)
- Los Angeles Times (1881–1990)
- The Louisville Courier-Journal (1830–1922)
- Minneapolis Tribune (1867–1922)
- The Nashville Tennessean (1812–1922)
- Newsday (1940–1985)
- New York Amsterdam News (1922–1993)
- The New York Times (1851–2010)
- New York Tribune (1841–1962)
- The Norfolk Journal & Guide (1921–2003)
- The Philadelphia Tribune (1912–2001)
- Pittsburgh Courier (1911–2002)
- San Francisco Chronicle (1865–1922)
- The Scotsman (1817–1950)
- St. Louis Post-Dispatch (1874–1922)
- The Times of India (1838–2004)
- Toronto Star (1894–2012)
- The Wall Street Journal (1889–1996)
- The Washington Post (1877–1997)
- Chinese Newspapers Collection (1832–1953)
- Advanced Technologies Database with Aerospace
- Aerospace Database
- AIDS & Cancer Research Abstracts
- Algology Mycology and Protozoology Abstracts (Microbiology C)
- Aluminium Industry Abstracts
- American Periodicals Series
- Animal Behavior Abstracts
- ANTE: Abstracts in New Technology & Engineering
- Applied Social Sciences Index and Abstracts (ASSIA)
- Aquatic Sciences & Fisheries Abstracts (ASFA)
- ARTbibliographies Modern (ABM)
- Arts & Humanities Full Text
- Bacteriology Abstracts (Microbiology B)
- Banking Information Source
- Biological Sciences
- Biotechnology and BioEngineering Abstracts
- Biotechnology Research Abstracts
- Black Studies Center
- British Humanities Index (BHI)
- Calcium & Calcified Tissue Abstracts
- Canadian Newsstand
- Ceramic Abstracts
- Chemoreception Abstracts
- Civil Engineering Abstracts
- Computer and Information Systems Abstracts (Module)
- Copper Technical Reference Library
- Corrosion Abstracts
- Design and Applied Arts Index (DAAI)
- Early European Books
- Earthquake Engineering Abstracts
- Ecology Abstracts
- Electronics & Communications Abstracts
- eLibrary Canada
- eLibrary Curriculum Edition
- eLibrary Elementary
- eLibrary Science
- Engineered Materials
- Engineering Research Database
- Entomology Abstracts
- Environment Abstracts
- Environmental Engineering Abstracts
- Environmental Science and Pollution Management
- ERIC PlusText
- Ethnic NewsWatch
- FIAF International Index to Film Periodicals Plus
- Gannett Military Newspapers
- Gannett Newspapers
- Genetics Abstracts
- Health & Safety Science Abstracts
- History Study Center
- Immunology Abstracts
- Industrial and Applied Microbiology Abstracts (Microbiology A)
- International Bibliography of Art (IBA)
- International Bibliography of the Social Sciences (IBSS)
- International Index to Black Periodicals
- International Index to Music Periodicals
- International Index to the Performing Arts
- Library and Information Science Abstracts (LISA)
- Linguistics and Language Behavior Abstracts (LLBA)
- Literature Online
- Literature Online Reference Edition
- Materials Business File
- Materials Research Database
- Mechanical & Transportation Engineering Abstracts
- MEDLINE with Full Text
- Meteorological & Geoastrophysical Abstracts
- Middle East Newsstand
- Neurosciences Abstracts
- Nucleic Acids Abstracts
- Oceanic Abstracts
- Oncogenes and Growth Factors Abstracts
- Periodicals Archive Online
- Periodicals Index Online
- Pharmaceutical News Index
- Physical Education Index
- Pollution Abstracts
- PRISMA (Publicaciones y Revistas Sociales y Humanísticas)
- Professional ProQuest Central
- ProQuest 5000
- ProQuest 5000 International
- ProQuest Accounting & Tax Database
- ProQuest Advanced Technologies & Aerospace Collection
- ProQuest Agricultural Science Collection
- ProQuest ANZ Newsstand
- ProQuest Aquatic Science Collection
- ProQuest Asian Business and Reference
- ProQuest Atmospheric Science Collection
- ProQuest Biological Science Collection
- ProQuest Career and Technical Education
- ProQuest Central
- ProQuest Computer Science Collection
- ProQuest Criminal Justice Periodicals Index
- ProQuest Discovery
- ProQuest Dissertations and Theses (formerly known as DAI, Dissertation Abstracts International)
- ProQuest Earth Science Collection
- ProQuest Education Journals
- ProQuest Engineering Collection
- ProQuest Entrepreneurship
- ProQuest Environmental Science Collection
- ProQuest Family Health
- ProQuest Health & Medical Complete
- ProQuest Health Management
- ProQuest Historical Annual Reports
- ProQuest International Newswires
- ProQuest Library Science
- ProQuest Materials Science Collection
- ProQuest Medical Library
- ProQuest Military Collection
- ProQuest Natural Science Collection
- ProQuest NewsStand
- ProQuest Nursing & Allied Health Source
- ProQuest Political Science
- ProQuest Polymer Science Collection
- ProQuest Professional Education
- ProQuest Psychology Journals
- ProQuest Public Health
- ProQuest Religion
- ProQuest Research Library
- ProQuest Science Journals
- ProQuest SciTech Collection
- ProQuest Social Science Journals
- ProQuest Sociology
- ProQuest Technology Collection
- Risk Abstracts
- SIRS Decades
- SIRS Discoverer
- SIRS Government Reporter
- SIRS Issues Researcher
- SIRS Renaissance
- Social Services Abstracts
- Sociological Abstracts
- Solid State and Superconductivity Abstracts
- State Packages
- Sustainability Science Abstracts
- Technology Research Database
- Toxicology Abstracts
- Udini by ProQuest
- US Hispanic Newsstand
- Virology and AIDS Abstracts
- Water Resources Abstracts
- Worldwide Political Science Abstracts
- "New CEO". ProQuest LLC. 2011.
- Power, Eugene B.; Robert Anderson (1990). Edition of One: The Autobiography of Eugene B. Power. Ann Arbor, Michigan: University Microfilms. pp. 128–142. ISBN 0-8357-0898-5.
- "Library of Congress 1999 press release". Loc.gov. January 22, 1999. Retrieved 2012-03-13.
- "ProQuest (brand)". proquest.com.
- "ProQuest Information and Learning has acquired Copley Publishing Group, Inc.". findarticles.com. May 2004.
- "ProQuest acquires RefWorks". ProQuest LLC. January 18, 2008. Retrieved February 2, 2012.
- ""ProQuest acquires Dialog". ProQuest LLC. July 1, 2008. Retrieved March 6, 2009.
- "ProQuest signs agreement to acquire Dialog business from Thomson Reuters". scientific.thomsonreuters.com. June 12, 2008. Retrieved January 18, 2009.
- "ProQuest Acquires Acclaimed Congressional Information Service and University Publications of America from LexisNexis". ProQuest LLC. November 30, 2010. Retrieved December 7, 2010.
- Fitzpatrick, Sean (January 8, 2011). "ProQuest acquires ebrary". American Libraries. Retrieved 2012-02-03.
- ProQuest. "Title List System". Products & Services. Retrieved July 1, 2012.
- ProQuest. "CSA Title Lists". Products & Services. Retrieved July 1, 2012.
- ProQuest. "Chadwyck-Healey Title Lists". Products & Services. Retrieved July 1, 2012.
- ProQuest. "eLibrary Title Lists". Products & Services. Retrieved July 1, 2012.
- ProQuest. "SIRS Title Lists". Products & Services. Retrieved July 1, 2012.
- Eugene B. Power, Edition of One: The Autobiography of Eugene B. Power, Founder of University Microfilms, 1990 ISBN 0-8357-0898-5.