Following the attacks of September 11, 2001, the Environmental Protection Agency and other government agencies removed information from their websites that they feared could invite attacks on critical public and private infrastructure. Accordingly, the benefits and costs of environmental information disclosure programs have come under increasing scrutiny. This article describes a framework for examining these benefits and costs and illustrates the framework through brief case studies of two information disclosure programs: risk management planning and materials accounting. The article outlines what we know and still need to find out about information disclosure programs in order to appropriately balance benefits and costs.