The Cook Out 400 is an annual NASCAR Cup Series stock car race held at the 0.526-mile (0.847 km) Martinsville Speedway in Ridgeway, Virginia. It is the first of two Cup Series races at the track, the other one being the Xfinity 500 in the NASCAR playoffs.

Martinsville Speedway is a stock car racing short track in Ridgeway, Virginia, just south of Martinsville. The track was also one of the first paved oval tracks in stock car racing, being built in 1947 by partners H. Clay Earles, Henry Lawrence, and Sam Rice, nearly a year before NASCAR was officially formed. It is also the only race track that has been on the NASCAR circuit from its beginning in 1948. Along with this, Martinsville is the only oval track on the NASCAR circuit to have asphalt surfaces on the straightaways and concrete to cover the turns. At 0.526 miles (847 m) in length, it is the shortest track in the NASCAR Cup Series. It is owned by NASCAR.