Why be moral? One possible, and compelling answer is that to act morally is in an agent's self-interest. Such an answer can be either elevationist (broadly speaking the Aristotelian/Platonic approach) where self-interest is elevated to coincide with living the good life, or reductionist where morality is defined as acting in an agent's self-interest. Elevationist moral theories appear flawed. If you are in possession of information that, if divulged, will bring about the deaths of others then it may be virtuous to stay silent. However, if staying silent results in you being slowly tortured to death in an effort to extract the information then it seems bizarre to suggest that in doing so you are flourishing, happy, or acting out of self-interest. Reductionist moral theories, acting for the 'good of self' rather than the 'good of others', are widely considered to be the antithesis of morality. Moral philosophers tend to attack such positions claiming that the doctrine of egoism is unworkable. It is commonly claimed that any theory which recommends 'an agent do x if x is in the agent's best interest' is inconsistent, incoherent, or contradictory and fails to meet the basic requirements of a moral theory (notably the requirement of universalisability). I begin this thesis with an examination of ethical egoism in its most widely known consequentialist form; i.e. an agent ought to act so as to bring about the best consequences for that agent. I examine the major criticisms of this theory and demonstrate that the axioms of egoism can be developed so as to overcome these criticisms. I argue that consequentialist based ethical egoism is coherent, consistent and noncontradictory. However, I go on to argue that while egoism can be formulated in a manner that overcomes all the aforementioned analytic criticisms it is a flawed moral theory in that within certain contexts the action deemed morally correct by egoism is, as a matter of fact, morally pernicious. That a theory contains a flaw is not reason enough to discard the entire theory and I go on to contend that the problem with egoism is the consequentialist approach, not the fact that it is based on self-interest. In Part 2 of the thesis I abandon the consequentialist approach and examine the possibility of a flourishing-based form of ethical egoism. I further develop the axioms of egoism established in Part 1 through an examination of the concept of flourishing (as commonly associated with virtue ethics). Ultimately I tread a path between the consequentialist and elevationist positions. While I do not elevate self-interest to acting virtuously I do contend that an egoist must adopt certain virtues if that egoist is to have the best possibility to flourish. However, I further contend that an egoist ought to act so as to promote that which the egoist values and that this agent-relative hierarchy of values, which necessarily contains certain virtues, determines the manner in which an egoist ought to act.