...This essay draws on the new social norms literature to examine one of the possible reasons for the public misperceptions about the sources of the remaining environmental problems. The essay suggests that one of the insights of the social norms literature, the influence of social meaning on social norms, may shed light on these misperceptions and may enrich our understanding of the difficulties encountered by efforts to control second generation sources. In particular, this essay examines two principal social meanings that appear to have been conveyed by the command and control system. The first social meaning is the conventional notion that pollution is bad.' This social meaning may have been conveyed directly through the prescriptions of the command and control statutes, and it may have promoted the development of social norms against pollution. These norms may in turn have facilitated the development of the command and control system. In fact, fear that this social meaning will be undermined underlies much of the criticism of emissions trading systems...