The Sons of the American Revolution (SAR), formally the National Society of the Sons of the American Revolution (NSSAR), is a federally chartered patriotic organization. The National Society, a nonprofit corporation headquartered in Louisville, Kentucky, was formed in New York City on April 30, 1889. Its objectives are to maintain and extend "the institutions of American freedom, an appreciation for true patriotism, a respect for our national symbols, the value of American citizenship, [and] the unifying force of 'e pluribus unum' that has created, from the people of many nations, one nation and one people."

The members of the society are male descendants of people who served in the American Revolutionary War or who contributed to establishing the independence of the United States. It is dedicated to perpetuating American ideals and traditions, and to protecting the United States Constitution. The official recognition of Constitution Day, Flag Day, and Bill of Rights Day were established through its efforts. The society has members in the United States, Canada, France, Germany, Spain, Switzerland, and the United Kingdom.

The organization is distinct from the Sons of the Revolution, a separate patriotic organization founded on February 22, 1876, by businessman John Austin Stevens and members of the Society of the Cincinnati. Sons of the American Revolution founder William Osborn McDowell disagreed with the Sons of the Revolution requirement at that time that all state societies were to be subordinate to the New York Society.

The first organization of descendants of Revolutionary War patriots was established in San Francisco, in 1876. A group of men who were descendants of American Revolutionary War veterans gathered to celebrate the centennial of the Declaration of Independence and the founding of the United States. They also wanted to honor the men and women who pledged their lives, fortunes, and livelihood to the striving for independence from Great Britain. This group formed an organization called the Sons of Revolutionary War Sires. There is, however, no direct link between the Sons of Revolutionary War Sires and the Sons of the American Revolution except that members of the Sons of Revolutionary War Sires were permitted to join the Sons of the American Revolution after its founding in 1889.

The organization's founding can be traced to the Sons of the Revolution, a New York City society that was organized in 1876. Sons of the Revolution was founded by John Austin Stevens, who envisioned an aristocratic social and hereditary organization along the lines of the Society of the Cincinnati.

In 1889, William O. McDowell, a New Jersey financier and businessman, organized the New Jersey Society of the Sons of the Revolution but was unwilling to accept the Sons of the Revolution's requirement that other state societies be subordinate to the New York society. McDowell also wanted the society to become more of a mass movement of descendants of Revolutionary patriots rather than an exclusive social club.

McDowell organized the Sons of the American Revolution at Fraunces Tavern in New York City, on April 30, 1889, the same year as the centennial anniversary of the first inauguration of George Washington as the nation's first president in 1789. McDowell was the organization's first member. In addition to organizing the Sons of the American Revolution, McDowell worked with six women to organize Daughters of the American Revolution, a national organization for women who descend from American Revolution era figures.

On June 9, 1906, Sons of the American Revolution was formally granted a congressional charter by an act of Congress under Title 36 of the United States Code. The act was signed by U.S. President Theodore Roosevelt, who was a member.