Legal scholarship regarding tax exempt nonprofit entities is meager at best. Although some excellent treatises, book chapters, and journal articles have been written, the body of scholarship relating to these entities is not nearly as healthy and robust as the scholarship relating to their for-profit companions. This is especially troubling considering that nonprofit entities help to improve our society in a myriad of different ways.This Article seeks to fill a void in the existing scholarship by offering an essentialist theory for charitable tax exempt nonprofit corporations that helps to explain the essence of these entities. Beyond the purely academic metaphysical inquiry into what is a corporation, understanding the essential nature of these corporations is important because it helps to determine how they should interact with society, what rights they should have, and how they should be governed by the law. This discussion is especially timely because the recent opinions by the Supreme Court of the United States in Citizens United and Hobby Lobby have reinvigorated the debate over the essence of the corporation.This Article breaks new ground by offering a new essentialist theory of the corporation, which shall be termed “collaboration theory.” The decades of debate over the essence of for-profit corporations has coalesced into three prevailing theories of the corporation, i.e., the artificial entity theory, the real entity theory, and the aggregate theory. The problem is that none of these prevailing theories fully answers the question of what is a corporation.Collaboration theory suggests that charitable tax exempt nonprofit corporations are collaborations among the state governments, federal government, and individuals to promote the public good. Unlike the prevailing theories of the corporation, collaboration theory explains both how and why charitable tax exempt nonprofit corporations exist, which provides a fuller and more robust understanding of these corporations. Collaboration theory advances the existing scholarship by finally offering an essentialist theory for nonprofit corporations, and it shows remarkable promise for understanding the essential nature of for-profit corporations as well.