The Noble and Greenough School, commonly known as Nobles, is a coeducational, nonsectarian day and five-day boarding school in Dedham, Massachusetts, a suburb of Boston. It educates 638 boys and girls in grades 7–12. The school's 187-acre (0.76 km²) campus borders the Charles River.

In 1866, Washington University in St. Louis Latin professor George Washington Copp Noble returned to Boston and founded Noble's Classical School as an all-boys college-preparatory school. He renamed the school to Noble & Greenough School in 1892, when his son-in-law James Greenough joined the faculty. The school was originally a for-profit entity run by the Noble family, but in 1913, after Greenough's death, a coalition of Nobles alumni purchased the school from Noble and reorganized the school as a nonprofit corporation under the control of a board of trustees.

Nobles historically drew most of its students from "the fashionable families of Greater Boston"; sociologist Digby Baltzell called it "Proper Boston's most exclusive day school." The school primarily catered to members of the Episcopal Church; a 1954 alumnus recalled that when he was at Nobles, there were only two non-Episcopalian students. (A Unitarian, John Richardson '04, served as president of the Nobles board from 1921 to 1964.)

In its early days, Nobles cycled through a series of buildings in Boston. In 1922, at the peak of the country day school movement, the school moved to suburban Dedham, where it has remained ever since. (In the 1920s, Nobles, Roxbury Latin, and Belmont Hill all set up campuses in the Boston suburbs.) The property had previously been the estate of Albert W. Nickerson, a Nobles grandparent, who had commissioned Frederick Law Olmsted to lay out the site. Nickerson's Richardsonian Romanesque mansion, popularly dubbed "the Castle," now serves as the school's dining hall.

In 1926, shortly after moving to Dedham, Nobles discontinued its primary school program. In response, a coalition of Nobles parents (including Joseph Kennedy Sr.) started the Dexter School. One of the Nobles elementary school students who transferred to Dexter was third-grader John F. Kennedy.

Nobles is descended from various Boston college-preparatory day schools, all of which primarily prepared students for the Harvard College entrance examinations. The curriculum of these schools was primarily classical, as until 1887, Harvard required applicants to study both Latin and Greek. Moreover, even after 1887, Harvard still required applicants to demonstrate either "an elementary working knowledge" of Latin and Greek, or advanced preparation in mathematics or natural sciences. According to James Greenough, in practice, only students "especially adapted to the study of mathematics and natural science" could get into Harvard without studying the classics.

In the nineteenth century, most public high schools lacked the resources to employ a classics teacher. By contrast, classically oriented private schools like Nobles and its predecessors were very successful at preparing students to pass Harvard's entrance exams.

Nobles claims the history and alumni of Volkmann School. In 1966, Volkmann's alumni erected a monument to their alma mater on the Nobles campus. However, Nobles does not claim Dixwell's 1851 foundation date.