In this chapter I am concerned with a second main category of social actions, namely social norms of action. In order to focus my discussion I will stipulate at the outset that social norms as I understand them have the following characteristic features. First, they are regularities in action, or inaction. Second, social norms are not qua social norms, explicit rules or laws. They are not, qua social norms, explicitly formulated; nor do they, qua social norms, emanate from any formal authority or have any formal sanctions attached to them. Social norms are not necessarily laws. As it happens, many social norms are in addition laws, and I will consider the relationship between laws and social norms in the penultimate section of this chapter, entitled Social Norms and Laws. Third, social norms have a normative dimension in the sense that participating agents believe or feel that they ought to or, more often, ought not to perform the actions prescribed, or proscribed, by the norm. This normative dimension is not merely that implied by instrumental rationality; it is not simply that on pain of irrationality one ought to do what realises one's ends. Nor is this normative dimension, at least prima facie, prudential in character – agents do not conform because they believe it is in their self-interest – nor does it, prima facie, simply consist of feelings of sympathy for others. Fourth, the normative dimension of social norms provides agents who accept those norms with reasons for action, and I will consider this relationship in the final section of this chapter, entitled Social Norms and Practical Reason.