Executive Order (E.O.) 12866 on "Regulatory Planning and Review," issued in September 1993, describes the principles and procedures by which the Office of Management and Budget's Office of Information and Regulatory Affairs (OIRA) reviews hundreds of significant proposed and final agency regulations on behalf of the President before they are published in the Federal Register. On January 18, 2007, President George W. Bush issued E.O. 13422, making the most significant amendments to E.O. 12866 since it was published. The changes made by this new executive order are controversial, characterized by some as a "power grab" by the White House that undermines public protections and lessens congressional authority, and by others as "a paragon of common sense and good government." The most important changes made to E.O. 12866 by E.O. 13422 fall into five general categories: (1) a requirement that agencies identify in writing the specific market failure or problem that warrants a new regulation, (2) a requirement that each agency head designate a presidential appointee within the agency as a "regulatory policy officer" who can control upcoming rulemaking activity in that agency, (3) a requirement that agencies provide their best estimates of the cumulative regulatory costs and benefits of rules they expect to publish in the coming year, (4) an expansion of OIRA review to include significant guidance documents, and (5) a provision permitting agencies to consider whether to use more formal rulemaking procedures in certain cases. This report discusses each of these changes, noting areas that are unclear and the potential implications of the changes, and provides background information on presidential review of rules. It concludes by noting that the significance of the changes made to the review process by E.O. 13422 may become clear only through their implementation, and notes some areas of potential congressional interest. The changes made by this executive order represent a clear expansion of presidential authority over rulemaking agencies. In that regard, E.O. 13422 can be viewed as part of a broader statement of presidential authority presented throughout the Bush Administration. The report will be updated as necessary to reflect legislative or executive branch actions relevant to the implementation of the executive order.