Ordered social life requires rules of conduct that help generate and preserve peaceful and cooperative interactions among individuals. The problem is that these social rules impose costs. They prohibit us from doing some things we might see as important and they require us to do other things that we might otherwise not do. The question for the ... contractarian is whether the costs of these social rules can be rationally justified. I argue that traditional contract theories have tended to underestimate the importance of evaluating the cost of enforcement and compliance in the contract procedure. In addition, the social contract has been understood narrowly as a method of justifying specifically moral or political rules. I defend a broader version of contractarianism as a justificatory model that can be used to evaluate any set of social rules or institutions that impose costs on agents. In so doing, I argue that contractarianism is a general method of evaluating and justifying the rules that order the structure of social life.