Abstract: Although published in 1970, The Costs of Accidents was written in the 1960s. In its boldness, its brilliance, and its progressive aspirations, the book is emblematic of the great society movement out of which it developed. Unimpressed with the legal and scholarly status quo, Calabresi set out to reinvent "accident law" in a manner that would best realize the set of values we care about most: minimizing accident costs within the limits set by justice. As confident as he was in his own framework, so was he critical of the value of the fault system which governed much of accident law then, and still does today. The bottom line is that the fault system is ill-suited to reducing primary accident costs. And, he argues, it is not even well suited to doing justice, so there is nothing to justify its ineptitude at cost reduction. We respond to Calabresi's critique both within his framework of primary cost reduction, and more broadly, and we articulate both responses in terms of social norms of responsibility. As a means of primary cost reduction, we argue, the internalization of social norms of safe conduct is critical. These norms are sustained, in part, by their entrenchment within a legal system that links liability to duties and duties with norms of responsibility. Moreover, the creation of "loci of responsibility", the articulation of obligations, and the provision of private individuals with an avenue of redress against one another are valuable aspects of the fault system even apart from their connection with primary cost reduction. The Costs of Accidents, by looking only at cost reduction and justice, entirely overlooks a range of values enjoyed by the fault system. In the inspiring enthusiasm to improve human welfare across the board, thinkers of the 1960s risked rendering "responsibility" a casualty of the Great Society. In following those thinkers, we must understand notions of responsibility as a friend, not a foe, of social improvement.