I should mention here that merely having a certain level of Security Clearance does not mean one is authorized to view classified information. To have access to classified information, one must possess the necessary two elements: A level of Security Clearance, at least equal to the classification of the information, AND, an appropriate "need to know" the information in order to perform their duties. Just because I have a SECRET Clearance, would not give me access to ALL Secret Information in the military. I would need to have a specific reason to know that information, before I could be granted access.
It's also worth mention that the Department of Defense (DOD) operates its security program separate from other government agencies, with its own procedures and standards. A TOP SECRET Clearance with the Department of Energy, for example, would not necessarily transfer to DOD.
In the United States Military, only United States Citizens can be granted a DOD Security Clearance.
Who Conducts Security Clearance Background Investigations?
Security Clearance Background Investigations for the Department of Defense (DOD) are conducted by the Defense Security Service (DSS). This includes background investigations for military personnel, civilian personnel who work for DOD, and military contractors. The Office of Personnel Management (OPM) conducts Security Clearance Investigations for most other branches of the Federal Government.
There were plans to transfer DOD Security Investigations from DSS to OPM, beginning in 2003. However, in March 2004, OPM announced those plans were scrapped. Whether or not OPM will take over the function in the future is unclear.
How are Security Clearances Granted?
Once it is determined that a military member requires a Security Clearance because of assignment or job, the individual is instructed to complete a Security Clearance Background Investigation Questionnaire. As of May 2001, DOD requires that this form be completed by use of a computer software program, known as EPSQ (Electronic Personnel Security Questionaire), instead of the old paper form, the SF-86.
However, it's not necessary to have the ESPQ program to see what questions are asked in the questionnaire. They are exactly the same as on the paper SF-86 (PDF File).