The 8th International 500-Mile Sweepstakes Race was held at the Indianapolis Motor Speedway on Monday, May 31, 1920.

Ralph DePalma held a two lap lead when the car stalled on lap 187. His riding mechanic Pete DePaolo ran to the pits to get a can of gasoline, thinking they were out of fuel. DePalma was able to get the car rolling again, and the two rejoined the race. However, during the delay, the lead went to Gaston Chevrolet. Chevrolet himself ran out of fuel on lap 197, but he was able to coast to the pits and refuel. Chevrolet held on to win. Seven months later, he was fatally injured in a crash at Beverly Hills.

Chevrolet won the race without a single tire change, a remarkable feat at the time. Chevrolet was accompanied by riding mechanic John Bresnahan. Chevrolet's victory was the last by a driver born outside of the United States until George Robson's victory in the 1946 running.

Four-lap (10 miles (16 km)) qualifying runs were introduced in 1920. Previously one-lap runs were used. Ralph DePalma won the pole position at 99.65 mph (160.37 km/h). None of his four laps matched the track record (104.78 mph (168.63 km/h)) set the previous year.

• For 1920, riding mechanics were required.^[5]
• First alternate: none^[6]