This dissertation is about legal and moral obligation. In response to the skeptic who questions a) whether there are any obligations at all and/or b) whether particular claims about obligations in particular situations are true, an argument will be advanced affirming the existence of certain societal obligations. These societal obligations are moral obligations and recognition of them is required for demonstrating the legitimacy of the exercise of power by legal institutions. The theories of obligation of H.A. Prichard and W.D. Ross will be criticized. These theories neglect certain dimensions of obligation and do not provide an adequate response to certain forms of skepticism about obligation. Cases in Anglo-American contract law will be presented to reveal the way courts justify imposing obligations on parties in lawsuits. An argument justifying the procedure of the courts will bring to light the societal obligations which are basic to other types of obligation. The theory of obligation will then be tested by applying it to situations in which questions about obligation arise. The example of Socrates in the Crito will be offered as an example of the theory in practice. Finally, there will be discussion of the importance of these societal obligations and discussion about the limits of the inquiry concluded.