The Barnes Foundation is an art collection and educational institution promoting the appreciation of art and horticulture. Originally in Merion, the art collection moved in 2012 to a new building on Benjamin Franklin Parkway in Philadelphia, Pennsylvania. The arboretum of the Barnes Foundation remains in Merion, where it has been proposed that it be maintained under a long-term educational affiliation agreement with Saint Joseph's University.

The Barnes was founded in 1922 by Albert C. Barnes, who made his fortune by co-developing Argyrol, an antiseptic silver compound that was used to combat gonorrhea and inflammations of the eye, ear, nose, and throat. He sold his business, the A.C. Barnes Company, just months before the stock market crash of 1929.

Today, the foundation owns more than 4,000 objects, including over 900 paintings, estimated to be worth about $25 billion. These are primarily works by Impressionist, Post-Impressionist, and Modernist masters, but the collection also includes many other paintings by leading European and American artists, as well as African art, antiquities from China, Egypt, and Greece, and Native American art.

In the 1990s, the Foundation's declining finances led its leaders to various controversial moves, including sending artworks on a world tour and proposing to move the collection to Philadelphia. After numerous court challenges, the new Barnes building opened on Benjamin Franklin Parkway on May 19, 2012. The foundation's current president and executive director, Thomas "Thom" Collins, was appointed on January 7, 2015.

Albert C. Barnes began collecting art as early as 1902, but became a serious collector in 1912. He was assisted at first by painter William Glackens, an old schoolmate from Central High School in Philadelphia. On an art buying trip to Paris, France, Barnes visited the home of Gertrude and Leo Stein where he purchased his first two paintings by Henri Matisse. In the 1920s, Barnes became acquainted with the work of other modern artists such as Pablo Picasso, Amedeo Modigliani and Giorgio de Chirico through his Paris art dealer Paul Guillaume.

On December 4, 1922, Barnes received a charter from the Commonwealth of Pennsylvania establishing the Barnes Foundation as an educational institution dedicated to promoting the appreciation of fine art and arboriculture. He purchased property in Merion at 50 Lapsley Lane from the American Civil War veteran and horticulturist Captain Joseph Lapsley Wilson, who had established an arboretum there in around 1880. He commissioned architect Paul Philippe Cret to design a complex of buildings, including a gallery, an administration building, and a service building. The Barnes Foundation officially opened on March 19, 1925.

The main building features several unusual Cubist bas-reliefs commissioned by Barnes from the sculptor Jacques Lipchitz. Elements of African art decorate the exterior wrought iron and the tile work created by the Enfield Pottery and Tile Works on the front portico of the building. Barnes built his home next to the gallery, which now serves as the administration building of the Foundation. His wife, Laura Leggett Barnes, developed the Arboretum of the Barnes Foundation and its horticultural education program in 1940.

In 1908, Barnes organized his business, the A.C. Barnes Company, as a cooperative, devoting two hours of the work day to seminars for his workers. They read philosophers William James, Georges Santayana, and John Dewey. Barnes also brought some of his art collection into the laboratory for the workers to consider and discuss. This kind of direct experience with art was inspired by the education philosophy of John Dewey and planted the seed that eventually grew into the establishment of the Barnes Foundation. The two met at a Columbia University seminar in 1917 becoming close friends and collaborators spanning more than three decades.