Editor's Summary: Individuals are the largest source of dioxin emissions, contribute almost one-third of all ozone precursor emissions, and are a far larger source of several other air toxics than all large industrial sources combined. Thus, after more than 30 years of regulation largely directed at industry, individual behavior has emerged as a leading source of pollution. Prof. Michael P. Vandenbergh argues that treating individual behavior as a discrete source of pollution can lead to the development of viable, innovative regulatory instruments that have the prospect of achieving pollution reductions at a relatively low cost. The creation of an individual toxic release inventory, for example, is one such tool. Drawing on the work of norms scholars and leading social psychologists, Professor Vandenbergh argues that environmental norm activation theory can identify the information that is most likely to induce changes in environmental behavior and can help policymakers develop new tools for inducing such change.