Kelley Blue Book, headquartered in Irvine, California, is the United States' largest automotive vehicle valuation company. The company's website is a source for new and used vehicle pricing and information. The company has become so identified with its services that the trademarked terms blue book and blue book value have become synonymous with a car's market value.

Kelley Blue Book Co., Inc., began as the Kelley Kar Company, a Los Angeles-based car dealership, in 1918. The dealership was founded by Les Kelley, an Arkansas-born businessman who started the dealership with three used Model T Fords and one employee, his 13-year-old brother Buster.

In order to obtain inventory, he began circulating lists of cars he wanted to acquire along with the price he was willing to pay for them. The price lists quickly became a trusted standard among Los Angeles area banks and car dealers.