Wellesley College is a private women's liberal arts college in Wellesley, Massachusetts, United States. Founded in 1870 by Henry and Pauline Durant as a female seminary, it is a member of the Seven Sisters Colleges, an unofficial grouping of women's colleges in the northeastern United States.

Wellesley enrolls approximately 2,500 students, including transgender, non-binary and genderqueer students since 2015. It contains 60 departmental and interdepartmental majors spanning the liberal arts, as well as over 150 student clubs and organizations. Wellesley athletes compete in the NCAA Division III New England Women's and Men's Athletic Conference. Its 500-acre (200 ha) campus was designed by Frederick Law Olmsted and houses the Davis Museum and a botanic garden.

Wellesley was founded by Pauline and Henry Fowle Durant, believers in educational opportunity for women, who intended that the college should prepare women for "great conflicts, for vast reforms in social life". Its charter was signed on March 17, 1870, by Massachusetts governor William Claflin. The original name of the college was the "Wellesley Female Seminary"; its renaming to Wellesley College was approved by the Massachusetts legislature on March 7, 1873. Wellesley first opened its doors to students on September 8, 1875. At the time of its founding, Wellesley College's campus was actually situated in Needham; however, in 1880 residents of West Needham voted to secede and in 1881 the area was chartered as a new town, Wellesley.

Wellesley College was a leading center for women's study in the sciences. Between 1875 and 1921, Wellesley employed more female scientists than any other U.S. institution of high education. After MIT, it was the second college in the United States to initiate laboratory science instruction for undergraduates. In early 1896, Sarah Frances Whiting, the first professor of physics and astronomy, was among the first U.S. scientists to conduct experiments in X-rays.

The first president of Wellesley was Ada Howard. There have been thirteen more presidents in its history: Alice Freeman Palmer, Helen Almira Shafer, Julia Irvine, Caroline Hazard, Ellen Fitz Pendleton, Mildred H. McAfee, Margaret Clapp, Ruth M. Adams, Barbara W. Newell, Nannerl O. Keohane (later the president of Duke University from 1993 to 2004), Diana Chapman Walsh, H. Kim Bottomly, and incumbent president Paula Johnson.

The original architecture of the college consisted of one very large building, College Hall, which was approximately 150 metres (490 ft) in length and five stories in height. It was completed in 1875. The architect was Hammatt Billings. College Hall was both an academic building and a residential building. On March 17, 1914, it was destroyed by fire, the precise cause of which was never officially established. The fire was first noticed by students who lived on the fourth floor near the zoology laboratory. It has been suggested that an electrical or chemical accident in this laboratory—specifically, an electrical incubator used in the breeding of beetles—triggered the fire.

A group of residence halls known as the Tower Court complex is located on top of the hill where the old College Hall once stood.

After the loss of the Central College Hall in 1914, the college adopted a master plan in 1921 and expanded into several new buildings. The campus hosted a Naval Reserve Officer Training program during the Second World War, and the College President Mildred McAfee took a leave of absence to lead the Women's Reserve of the U.S. Navy. She received the Distinguished Service Medal in 1945. Wellesley College began to significantly revise its curriculum after the war and through the late 1960s; in 1968, the college began its exchange programs between other colleges in the area such as MIT. In 2013 the faculty adopted an open-access policy to make its scholarship publicly accessible online.