Sensitive Security Information (SSI) is a category of sensitive but unclassified information under the United States government's information sharing and control rules. SSI is information obtained in the conduct of security activities whose public disclosure would, in the judgement of specified government agencies, harm transportation security, be an unwarranted invasion of privacy, or reveal trade secrets or privileged or confidential information. SSI is governed by Title 49 of the Code of Federal Regulations (CFR), parts 15 and 1520.

SSI was created to help share transportation-related information deemed too revealing for public disclosure between Federal government agencies; State, local, tribal, and foreign governments; U.S. and foreign air carriers; and others.

SSI is not a form of classification under Executive Order 12958 as amended; that is, it is not classified national security information in the sense of Top Secret, Secret or Confidential.