Are all government agencies part of cabinet departments?

No, not all government agencies are part of cabinet departments. While cabinet departments are major administrative units of the federal government, there are also independent agencies, regulatory commissions, and government corporations that operate outside of the cabinet structure. These entities have specific functions and varying degrees of autonomy from the executive branch. Examples include the Environmental Protection Agency (EPA), the Federal Communications Commission (FCC), and the United States Postal Service (USPS).