As the field of fast pyrolysis has matured, it has been accompanied by a kind of orthodoxy in its practice. Among these orthodoxies are the following: (1) oxygen should be excluded from the pyrolysis process; (2) little sugar is produced during pyrolysis; and (3) the major product of pyrolysis is a low-value emulsion in water. Adherence to these tenets is an impediment to the commercial development of fast pyrolysis. Over the past 15 years, research at Iowa State University’s Bioeconomy Institute has challenged these tenets with what might be called heterodoxy in the science and engineering of fast pyrolysis: adding oxygen, producing sugars, and fractionating bio-oil into valorized products. This paper reviews these new approaches to pyrolysis and concludes with an outlook for further developing them.