Interim-final rules are binding norms federal agencies adopt and make immediately effective without inviting prior public comment on a rulemaking proposal. The Administrative Procedure Act ordinarily requires the use of notice and comment procedures to adopt legislative rules, but agencies justify omitting the pre-adoption comment period by invoking the impracticability or public interest prongs of the APA's good cause exception to this requirement. An agency following this route may invite post-adoption comment on the rule, and then readopt it in final form after taking account of the public comments. Agencies use this methodology between 300 and 400 times each year. The paper makes an empirical examination of the frequency of use of interim-final rules and inquires why they are so commonly used. It analyzes legal problems arising out of their use (particularly problems arising out of the conjunction of the APA and other statutes constraining rulemaking procedure like the Regulatory Flexibility Act) and makes some policy recommendations. The article updates a consultant's report to the former Administrative Conference of the United States, that led to the adoption of ACUS Recommendation 95-4.