The Order of the Arrow (OA) is the honor society of Scouting America, composed of Scouts and Scouters who best exemplify the Scout Oath and Law in their daily lives as elected by their peers. It was founded as a camp fraternity by E. Urner Goodman, with the assistance of Carroll A. Edson, in 1915. Although it began without national approval, it was eventually admitted as an "Official Experiment" of Scouting America. In 1948, following an extensive review, it became a program of the organization.

Inducted members, known as Arrowmen or Brothers (regardless of gender; as Scouting America and its programs are open to all genders), are organized into local youth-led lodges that harbor fellowship, promote camping, and render service to scout councils and their communities. Each lodge corresponds to a council in the area. Lodges are further broken down into chapters, which correspond to districts within a council. Members wear identifying insignia on their uniforms, most notably the pocket flap that represents their individual lodge and the sash worn at official OA functions. The national organization sponsors several events, awards, and training functions in addition to lodge programming.

Scouting America maintains that the Order of the Arrow is not a secret organization. It instead utilizes the “attractiveness of the unknown” in its ceremonies to create a perception of mystery among non-members. There are three membership levels, each with its own ceremony: Ordeal, Brotherhood, and Vigil Honor. These ceremonies are recognition of a scout's leadership qualities, camping skills, and other Scouting ideals as exemplified by their elected peers. Additionally, "safeguarded” (privy only to members and approved, legitimately interested adults) symbols and handshakes are used to impart a sense of community. Since the 1980s, concerned parents, Scout leaders, and religious leaders may review the ceremonies through a process set by the OA, and parents can refuse for their child to take part in the ceremony as membership is voluntary.

The Order of the Arrow has foundations influenced by Freemasonry and previously used imagery commonly associated with American Indian cultures for its self-invented ceremonies. Native Americans have criticized the OA's various symbols and "rituals" as cultural appropriation based on non-Native stereotypes of American Indians. Its Freemason ties have also been source of debate, in spite of its systematic removal of masonic terminology in the 1930s to avoid offending religious groups.

The Order of the Arrow was started as a Camp Fraternity by E. Urner Goodman, newly assigned Director of Treasure Island Scout Reservation on the Delaware River and assistant Camp Director Carroll A. Edson under the name of Wimachtendienk Wingolauchsik Witahemui. It was seen as a way to improve the summer camp experience and to encourage older Scouts to continue attending the summer camp. It was not part of Scouting America at the time. The name was based on the Lënape dialect.

In 1921, the "known" lodges organized themselves under a Grand Lodge as inspired by the Freemasons. A new constitution was written and the ceremonies used in the early years were rewritten in 1921. Concern about fraternities excluding some youth was brought up the next year during the Second Biennial Conference of Scout Executives. One attendee, Dr. Tinney of Little Rock, AR stated,

I happen to be an ex-fraternity man. I have had experience where every boy in the camp is not given the opportunity - mind you I say the opportunity - to join that fraternity, which is certainly opposed to the idea of Scouting. If every man in camp is given that chance and not just a clique or coterie who call themselves together and form a fraternity, perhaps it might work advantageously.

Goodman had defended camp fraternities at the same conference and opposed a possible blanket ban on them. At the conclusion of the conference, the Order of the Arrow was adopted as an "Official Experiment" of Scouting America.