The notice of proposed rulemaking (NPRM) serves to inform the public that a Federal agency is considering a regulatory change. The NPRM must be published in the Federal Register unless all of the persons who would be subjected to the proposed change are named and either personally served or otherwise have actual notice. The NPRM describes the new rule or changes being considered in existing rules, and tells the public how they may participate in the rulemaking process. Most NPRMs now allow for a comment period of sixty days although the actual time may be shorter or longer. In most cases, the public is invited to participate by submitting written comments to the agency. If the agency plans to hold a public hearing, the time and place of the hearing are often announced in the NPRM. If the agency does not decide to hold a public hearing until after the NPRM is published, the hearing is usually announced in a separate Federal Register document.

No particular format is required for written comments. They may be as simple as a letter or postcard or as formal as a printed legal brief. Agencies are increasingly allowing comments to be filed electronically as well. Most agencies maintain all of the comments received on a particular NPRM in a single file, usually referred to as the "docket." Before an agency issues a final regulation, it is required to consider all comments it receives in response to an NPRM.