The distinction between intrinsic and extrinsic value can be traced back to Plato and Aristotle. I contend that the distinction has never been properly drawn. My main task is to formulate the distinction in a way that avoids the problems of the traditional formulations. ;After defending the traditional Moorean conception of intrinsic value against John Mackie's arguments from relativity and "queerness," and against recent attacks by Elizabeth Anderson and Shelly Kagan, I attempt to define two important types of extrinsic value (...) in terms of intrinsic value. First, I define instrumental value. The main problem with traditional definitions of instrumental value is that they fail to account for the fact that preventing something intrinsically evil from occurring seems to be just as worthwhile as bringing about something intrinsically good. I attempt to account for this fact by introducing a "contextualist" analysis of instrumental value. Next, I present and defend an analysis of contributory value. I compare contributory value with conditional intrinsic value, and present an argument to show that the notion of conditional intrinsic value faces problems that can be avoided by admitting the existence of contributory value. I then expand on the contextualist analysis of instrumental value, and provide an analysis of extrinsic value that explains what is common to instrumental and contributory value. I contend that my analysis can also account for other types of extrinsic value---for example, signatory value---and I defend my analysis against recent objections by Alastair Norcross involving the extrinsic values of actions. ;Finally, I argue that contributory value can help to solve a current problem in environmental ethics. The problem is this: how can it be that the last member of a species is more valuable than a similar member of a flourishing species ? I argue that diversity of goods increases the value of a whole; therefore, the last member of an endangered species has contributory value in virtue of its contribution to the world's biological diversity. (shrink)