Administrative rules and regulations are issued by government agencies in response to congressional laws. Regulations are published first in the Federal Register and then at the end of each year are incorporated into the Code of Federal Regulations.

RegInfo.gov: Where to find regulatory information

Federal Register Search (1994-current, GPO Access)
Federal Register Search (1936-current, HeinOnline, Yale only)
Federal Register web site (National Archives, Office of the Federal Register)
Regulations.gov Find, review, and submit comments on Federal documents that are open for comment and published in the Federal Register.

Code of Federal Regulations Search (1996-current, GPO Access)

List of CFR Sections Affected (1986-current, GPO Access)
The List of CFR Sections Affected lists proposed, new, and amended federal regulations that have been published in the Federal Register since the most recent revision date of a CFR title.

Research Guide to the Federal Register and the Code of Federal Regulations
(Law Librarian Society, Washington, DC.)

Federal Administrative Decisions and other Actions (University of Virginia School of Law)
Links to other administrative actions that are outside the scope of the Code of Federal Regulations or the Federal Register.