Friends Seminary is an independent K-12 school in Manhattan, New York, United States. The oldest continuously coeducational school in New York City, in recent years it has served approximately 800 students.

Friends Seminary is the oldest continuously operated, independent, co-educational day school in New York City. Serving students in kindergarten through twelfth grade, the School is chartered by the State of New York and is governed by a twenty-four-member Board of Trustees. Friends Seminary is the only Quaker school in Manhattan and draws upon a long and rich Quaker heritage, reflected in its commitment to the uniqueness of each individual student and its devotion to the ideals of simplicity, equality, service to others, diversity, personal integrity, and non-violent resolution of differences.

Friends Seminary, established by members of the Religious Society of Friends, whose members are known as Quakers, was founded in 1786 as Friends' Institute through a $10,000 bequest of Robert Murray, a wealthy New York merchant. It was located on Pearl Street in Manhattan and strived to provide Quaker children with a "guarded education." In 1826, the school was moved to a larger campus on Elizabeth Street. Tuition in that year was $10 or less per annum, except for the oldest students, whose families paid $20. (By 1915, tuition had risen to $250.) The school again moved in 1860 to its current location and changed its name to Friends Seminary.

In 1878, Friends Seminary was one of the earliest of schools to establish a Kindergarten. In 1925, it was the first private co-educational school to hire a full-time psychologist. M. Scott Peck, who transferred to Friends from Phillips Exeter in late 1952, praised the school's diversity and nurturing atmosphere. "While at Friends," he wrote, "I awoke each morning eager for the day ahead ... [A]t Exeter, I could barely crawl out of bed."

In 2015, based on recommendations made in 2005 by the Trustees of the New York Quarterly Meeting after completion of a study, the New York Quarterly Meeting reached consensus on the issue of incorporating the school and the New York Quarterly Meeting separately. Under the agreement, Friends Seminary will pay the New York Quarterly Meeting $775,000 annually, and both sides will contribute an additional $175,000 to a capital fund to preserve the historic buildings. The Quakers will continue naming half the members of the school's governing board, and the agreement establishes a six-person committee to foster the school's commitment to Quaker values.

The school's vision is "to prepare students to engage in the world that is and to help bring about a world that ought to be." It is currently guided by a mission statement adopted in 2015, a service learning statement adopted in 2004, a diversity and inclusion mission statement adopted in 2005, and a global education mission statement adopted in 2024. Friends Seminary is a member of New York's Independent School Diversity Network.

The school is divided into three sections:

The campus comprises six buildings. The largest building, known as Hunter Hall, built in 1964, holds classes for the entire Middle School, most of the Lower School and some of the Upper School. The building contains a basement-level gymnasium and cafeteria, library and media center, science laboratories, art studios, computer laboratories and classrooms for all grades.