The rule of law is a normative political ideal. This chapter presents two approaches to understanding it. The first is the legal essentialist approach, which derives an account of the rule of law from an account of the essence of legality and legal systems. The second is the limited government approach, which derives an account from a normative theory proposing a role for law in opposing and negating the arbitrary power of persons over others. The chapter contends that the latter approach is more persuasive than the former. However, and despite recent refinements, the approach has a legacy of libertarian thinking and has not acknowledged what the author of this chapter refers to as a regulatory conception of the rule of law which has a prominent social dimension. The social dimension entails a duty founded upon the rule of law ideal to legally regulate private arbitrary powers whose exercise allows some to impose coercion as well as non-consensual exploitation on others. The regulatory conception and its social dimension help us understand the appropriate relationship between the rule of law and human rights, the welfare state, and democracy.