Editor's Summary: In the past decade, EPA and over 20 states have created voluntary environmental leadership programs designed to recognize and reward businesses that take steps that go beyond compliance with the strictures of environmental law. Environmental leadership programs seek not only to spur direct improvements to environment quality but also to advance broader social goals that may lead indirectly to environmental improvements, such as improving businessgovernment relationships and changing business culture. Measuring progress toward leadership programs' social goals is a particularly challenging but essential task if researchers and decisionmakers are to understand the full impacts of these programs. In this Article, Jonathan C. Borck, Cary Coglianese, and Jennifer Nash present strategies for overcoming the three core challenges in evaluating the social effects of leadership programs and any voluntary environmental initiative: (1) defining appropriate measures of social goals; (2) inferring whether programs achieve those goals; and (3) linking social effects to environmental outcomes. Only through careful attention to these three empirical issues will it be possible to rule out alternative explanations and determine whether environmental leadership programs are truly generating their intended positive social effects as well as improvements to the environment.