Although science has been incapable to come up with any breeding system that certificates the birth of a champion, breeders over the time have produced a progressively percentage of thoroughbreds that are winners on the racetrack by following one basic rule. The first is that thoroughbreds with superior racing aptitude are more likely to produce offspring with better racing ability.

Male thoroughbreds (stallions) have the maximum breeding value because they can mate with about 40 mares a year. The worth of champions, especially winners of Triple Crown races, is so high that groups of investors called breeding syndicates may be formed. Each of the approximately 40 shares of the syndicate entitles its owner to breed one mare to the stallion each year. One share, for a great horse, may cost several million dollars. A share's owner may resell that share at any time.

Farms that manufacture foals for public sale are called commercial breeders. The most successful are E. J. Taylor, Spendthrift Farms, Claiborne Farms, Gainsworthy Farm, and Bluegrass Farm, all in Kentucky. Farms that create foals to race themselves are called home breeders, and these include such famous stables as Calumet Farms, Elmendorf Farm, and Green-tree Stable in Kentucky and Harbor View Farm in Florida.