Heritage Chickens as defined here, are chickens which have a historical or contemporary use in the US, and which are still obtainable, and free of genetic or behavioral issues which interfere with sustainability.

Where a standard breed also has a bantam breed of the same name, the bantam breed is typically not listed, due to the varied ways in which bantam breeds are created. The characteristics of a bantam and a standard sized chicken of the same breed may be radically different.