Pursuant to a congressional request, GAO reviewed the regulatory review process, focusing on the Office of Information and Regulatory Affairs (OIRA) and four regulatory agencies, the Department of Housing and Urban Development (HUD) and Department of Transportation (DOT), the Department of Labor's Occupational Safety and Health Administration (OSHA), and the Environmental Protection Agency (EPA), and on whether: (1) the regulatory agencies had identified for the public the substantive changes made to their regulations between the draft they submitted to OIRA and the regulatory actions they subsequently anunced; (2) the regulatory agencies identified for the public the changes made to their regulations at the suggestion or recommendation of OIRA; and (3) OIRA had made available to the public all documents exchanged between OIRA and the selected agencies during OIRA's review.