The Livestock Conservancy maintains a list of Heritage Chicken breeders in its Breeders Directory. You can visit the online directory or if you wish to receive a printed copy please consider joining the Conservancy.
Some Heritage Chickens can be obtained from hatcheries. Below is a downloadable list of chicken hatcheries. The Livestock Conservancy encourages contacting the hatchery directly to determine the breeds of birds available and to determine whether these are in fact Heritage Chickens.