As regulators increasingly embrace cooperative approaches to governance, voluntary public-private partnerships and self-regulation programs have proliferated. However, because few have been subjected to robust evaluation, little is known about whether these innovative approaches are achieving their objectives. In the context of a nationwide self-policing program that encourages companies to voluntarily self-disclose regulatory violations, we examine the behaviors of facilities and regulators to gain empirical insights on the theoretical promise of self-policing. We find that regulators reduce their scrutiny over selfpolicing facilities, and especially over facilities with strong past compliance records. We also find that self-policing is associated with subsequent improvements in compliance records.