Despite serving as the principal basis of U.S. climate policy over the past two decades, corporate voluntary environmental programs have been subject to quite limited evaluation. The self-selection of participants—an essential element of such initiatives—poses particular challenges to...

We synthesize and review retrospective analyses of federal air quality regulations to examine the contributions of the Clean Air Act to the vast air quality improvements seen since 1970. Geographic heterogeneity in stringency affects emissions, public health, compliance costs, and employment....