The Art Institute of Chicago is a private, nonprofit art museum in Grant Park, Chicago, Illinois, United States.

Founded in 1879, it is one of the oldest and largest art museums in the United States. The museum is based in the Art Institute of Chicago Building in Chicago's Grant Park. Its collection, stewarded by 11 curatorial departments, includes works such as Georges Seurat's A Sunday on La Grande Jatte, Pablo Picasso's The Old Guitarist, Edward Hopper's Nighthawks, and Grant Wood's American Gothic. Its permanent collection of nearly 300,000 works of art is augmented by more than 30 special exhibitions mounted yearly that illuminate aspects of the collection and present curatorial and scientific research. The land of the institute is publicly owned by the city of Chicago and administered by the Chicago Park District.

As a research institution, the Art Institute also has a conservation and conservation science department, five conservation laboratories, and Ryerson and Burnham Libraries, one of the nation's largest art history and architecture libraries.

The museum's building was constructed for the 1893 World's Columbian Exposition and, due to the growth of the collection, several additions have occurred since. The Modern Wing, designed by Renzo Piano, is the most recent expansion, and when it opened in 2009 it increased the museum's footprint to nearly one million square feet. This made it the second largest art museum in the United States, after the Metropolitan Museum of Art in New York City.

The School of the Art Institute of Chicago is legally part of the Art Institute of Chicago, making it one of the few remaining unified arts institutions in the United States.