Many firms conduct “environmental audits” to test compliance with a complex array of environmental regulations. Commentators suggest, however, that self-auditing is not as common as it should be, because firms fear that what they find will be used against them. This article analyzes self-auditing as a two-tiered incentive problem involving incentives both to test for and to effect compliance. After demonstrating the inadequacy of conventional remedies, we show that incentives can be properly aligned by conditioning fines on firms’ investigative effort. In practice, however, the regulator may not be able to observe such effort. Accordingly, we propose and evaluate the use of three observable proxies for self-investigation: the manner in which the regulator detected the violation; the firm’s own disclosure of violations; and the firm’s observed corrective actions. Each method has its own efficiency benefits and informational requirements, and each is distinct from EPA’s current audit policy.