Studies of liver regenerative processes have gained new prominence, generated from analyses of genetically engineered animal models, the transplantation of human livers, and the surging interest in stem cells. These studies gave rise to expectations regarding the practical applications of research on the mechanisms of liver regeneration that were unthinkable just a few years ago. As the field expanded to a broader audience, this new knowledge also brought confusion and often misinterpretations regarding the cellular mechanisms responsible for liver regeneration in different types of hepatic growth processes. This article is a brief review of the role of hepatocytes, oval cells (see box for nomenclature), and bone marrow cells in liver regeneration and repopulation. This topic has generated great excitement, a good deal of noise, much controversy, and many surprises. The review of the rapidly expanding literature presented here, particularly as it deals with stem cells, was guided by a few principles:(1) be wary of dogma1 and of overinterpretation of data;(2) a “new discovery” may be a true new finding, but it may simply be the repackaging of an old discovery; and (3) an exciting story is not necessarily a true story.