A preference theory is a philosophical theory that the satisfaction of preferences is the only thing that matters in contributing to well-being. Well-being can be seen as what people ultimately want to achieve; the “ultimate good”1. In terms of preference theory, to achieve the state of well-being one must have one's preferences satisfied. Preference theories can be divided into two distinct categories, actual preference theory and ideal preference theory2. Actual preference theory is concerned with people's actual preferences, regardless of misinformation or irrationality, while ideal preference theory is interested in what we would “hypothetically” prefer, if we were fully informed and rational3. In this essay, I will argue against the explanation of well-being that effective preference theory presupposes, and I will try to demonstrate that it is wrong by showing that the satisfaction of preferences does not always have consequences favorable to well-being, and therefore the explanation of well-being provided by effective preference theory actual preferences is ultimately wrong. Effective preference theory states that well-being can be produced by satisfying one's preferences. So, if your preference is fulfilled, you are inevitably better off, because as a result of fulfilling your preference you experience well-being. It therefore seems undeniable to state that, according to preference theory, it is necessary to experience well-being if one's preference is satisfied. However, this view of well-being appears to have a serious flaw. If an agent is not aware of the satisfaction of her preferences, does she still experience well-being? Logic and rationality should tell us no, however real preference theory seems to disagree with this statement, and I… half of the article… a concept of well-being. Overall, the fusion of the inconsistencies and errors that I have attempted to highlight with my arguments proves my original hypothesis, namely that the theory of effective preferences does not offer the correct explanation of well-being, because the arguments show that the realization of a preference does not always produce consequences favorable to well-being. Word Count: 2134References1. Crisp, Roger, "Well-Being", The Stanford Encyclopedia of Philosophy, Summer 2013 Edition), Edward N. Zalta (ed.), URL=.2. Kagan, Shelly. 1998. “The Good” in Normative Ethics. Oxford: Westview Press3. Feldmann, Fred. 2004. “The search for the good life” in Pleasure and the Good Life. Oxford: Oxford University Press