How do I establish veteran eligibility? 

The preferred method is the DD Form 214, Certificate of Release or Discharge from Active Duty. If the DD Form 214 is not available, any discharge document showing other than dishonorable service can be used. The DD Form 214 may be obtained by filling out a Standard Form 180 and sending it to: 

National Personnel Records Center (NPRC) 
9700 Page Blvd. 
St Louis, MO 63132 

The Standard Form 180 may be obtained from the National Records Center or visit their website for more information.