Princeton University is a private Ivy League research university in Princeton, New Jersey, United States. Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution. The institution moved to Newark in 1747 and then to its Mercer County campus in Princeton nine years later. It officially became a university in 1896 and was subsequently renamed Princeton University.

The university is governed by the Trustees of Princeton University and has an endowment of $37.7 billion, the largest endowment per student in the United States. Princeton provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences, and engineering to approximately 8,500 students on its main campus spanning 600 acres (2.4 km²) within the borough of Princeton. It offers postgraduate degrees through the Princeton School of Public and International Affairs, the School of Engineering and Applied Science, the School of Architecture and the Bendheim Center for Finance. The university also manages the Department of Energy's Princeton Plasma Physics Laboratory and is home to the NOAA's Geophysical Fluid Dynamics Laboratory. It is classified among "R1: Doctoral Universities – Very high research activity" and has one of the largest university libraries in the world.

Princeton uses a residential college system and is known for its eating clubs for juniors and seniors. The university has over 500 student organizations. Princeton students embrace a wide variety of traditions from both the past and present. The university is an NCAA Division I school and competes in the Ivy League. The school's athletic team, the Princeton Tigers, has won the most titles in its conference and has sent many students and alumni to the Olympics.

As of October 2025, 81 Nobel laureates, 16 Fields Medalists and 17 Turing Award laureates have been affiliated with Princeton University as alumni, faculty members, or researchers. In addition, Princeton has been associated with 21 National Medal of Science awardees, 5 Abel Prize awardees, 11 National Humanities Medal recipients, 217 Rhodes Scholars, 137 Marshall Scholars, and 62 Gates Cambridge Scholars. Two U.S. presidents, twelve U.S. Supreme Court justices (three of whom serve on the court as of 2010^[update]) and numerous living industry and media tycoons and foreign heads of state are all counted among Princeton's alumni body. Princeton has graduated many members of the U.S. Congress and the U.S. Cabinet, including eight secretaries of state, three secretaries of defense and two chairmen of the Joint Chiefs of Staff. Princeton alumni also include 113 athletes who competed in the Olympics, winning 19 gold medals, 24 silver medals, and 23 bronze medals.

Princeton University, founded as the College of New Jersey, was shaped much in its formative years by the "Log College", a seminary founded by the Reverend William Tennent at Neshaminy, Pennsylvania, in about 1726. While no legal connection ever existed, many of the pupils and adherents from the Log College would go on to financially support and become substantially involved in the early years of the university. While early writers considered it as the predecessor of the university, the idea has been rebuked by Princeton historians.

The founding of the university itself originated from a split in the Presbyterian church following the Great Awakening. In 1741, New Light Presbyterians were expelled from the Synod of Philadelphia in defense of how the Log College ordained ministers. The four founders of the College of New Jersey, who were New Lights, were either expelled or withdrew from the Synod and devised a plan to establish a new college, for they were disappointed with Harvard and Yale's opposition to the Great Awakening and dissatisfied with the limited instruction at the Log College. They convinced three other Presbyterians to join them and decided on New Jersey as the location for the college, as at the time, there was no institution between Yale College in New Haven, Connecticut, and the College of William & Mary in Williamsburg, Virginia; it was also where some of the founders preached. Although their initial request was rejected by the Anglican governor Lewis Morrison, the acting governor after Morrison's death, John Hamilton, granted a charter for the College of New Jersey on October 22, 1746. In 1747, approximately five months after acquiring the charter, the trustees elected Jonathan Dickinson as president and opened in Elizabeth, New Jersey, where classes were held in Dickinson's parsonage. With its founding, it became the fourth-oldest institution of higher education in the United States, and one of nine colonial colleges chartered before the American Revolution. The founders aimed for the college to have an expansive curriculum to teach people of various professions, not solely ministerial work. Though the school was open to those of any religious denomination, with many of the founders being of Presbyterian faith, the college became the educational and religious capital of Scotch-Irish Presbyterian America.

In 1747, following the death of then President Jonathan Dickinson, the college moved from Elizabeth to Newark, New Jersey, as that was where presidential successor Aaron Burr Sr.'s parsonage was located. That same year, Princeton's first charter came under dispute by Anglicans, but on September 14, 1748, the recently appointed governor Jonathan Belcher granted a second charter. Belcher, a Congregationalist, had become alienated from his alma mater, Harvard, and decided to "adopt" the infant college. Belcher would go on to raise funds for the college and donate his 474-volume library, making it one of the largest libraries in the colonies.

In 1756, the college moved again to its present home in Princeton, New Jersey, because Newark was felt to be too close to New York. Princeton was chosen for its location in central New Jersey and by strong recommendation by Belcher. The college's home in Princeton was Nassau Hall, named for the royal William III of England, a member of the House of Orange-Nassau. The trustees of the College of New Jersey initially suggested that Nassau Hall be named in recognition of Belcher because of his interest in the institution; the governor vetoed the request.