This dissertation is structured in such a way as to gradually home in on the true theory of welfare. I start with the whole field of possible theories of welfare and then proceed by narrowing down the options in a series of steps. The first step, undertaken in chapter 2, is to argue that the true theory of welfare must be what I call a partly response independent theory. First I reject the entirely response independent theories because there are widely-shared intuitions suggesting that some psychological responses are indeed relevant to welfare. Then I reject the entirely response dependent theories because there are other central intuitions suggesting that our welfare is not determined solely by our psychological responses. Thus I reach the preliminary conclusion that welfare must involve some response independent (or objective) component. The next step is to consider the most promising theories in the partly response independent category. In particular, I formulate, refine and ultimately reject what seem to be the main monistic theories that have been proposed in this category. In chapter 4, I reject the Adjusted-Enjoyment Theories of Welfare because they cannot account for the claim that a life containing no pleasure or pain can still contain a positive amount of welfare (e.g. if it’s a particularly successful life). Then in chapters 5-7, I discuss Desire Satisfaction theories of welfare. I argue that even the most promising of these theories – e.g. Worthiness Adjusted Desire Satisfactionism – are problematic because they cannot accommodate the claim that a life containing no success with respect to worthwhile projects can still contain a positive amount of welfare (e.g. if it’s a particularly pleasant life). Finally, I suggest that in order to accommodate the intuitions that led to the rejection of all these other theories of welfare, what is needed is a multi-component theory. In the final chapter, I formulate a multi-component theory that is particularly promising. Not only does it avoid the problems of the monistic theories discussed earlier, but, by incorporating a number of novel mathematical devices, it avoids problems that undermine several other initially promising multi-component theories of welfare.