Each year the American Graded Stakes Committee of the Thoroughbred Owners and Breeders Association releases a list of stakes for thoroughbred horses. The Committee grades stakes and handicaps into three grades: Grade I, Grade II and Grade III. The largest races are Grade I. The committee uses as criteria for the grading:

• Purse Requirement: That the race has a purse of more than $75,000.
• Longevity: That the race has been run for two years under the same conditions.
• Drug Testing: That post race drug testing is managed by a governmental authority.
• Restrictions: That the race may be restricted only in age and gender.

As long as the race meets these requirements, the Committee grades on the overall quality of the previous fields and the performance of horses in the previous fields in stakes both prior to and after the race. For example: if the winner of the Breeders' Cup Turf raced in the Arlington Million then the race would almost certainly be a Grade One.