This chapter examines federal environmental rulemaking in the United States. Rulemaking – the process by which laws are taken and translated into more specific and detailed rules – is a seemingly technocratic exercise, yet one whose distributive consequences are highly significant since rules have the force of law and determine the nature of environmental regulation. We argue that environmental policy involves a high level of political contestation, as politicians and organized interests seek to influence the creation of environmental rules. We examine these accountability dynamics by analyzing the use of executive orders and shifts in administrative requirements, such as cost-benefit analysis. We also revisit key debates: whether the rulemaking process has become “ossified”, the role of federal courts in rulemaking, the effects of reforms, such as negotiated rulemaking and, finally, the role of the states in litigating rules. We conclude with thoughts about the contested nature of environmental regulation and the future of rulemaking.