I frequently get asked the difference between Social Security Disability and SSI. Social Security Disability is availble to people who have worked and paid taxes into the Social Security System. When you work you earn credits twords being eligible. You can earn up to 4 credits per year. You need a total of 40 credits to be eligible for benefits. For people who are very young you may need less than 40 credits. The date you are covered untill for disability is called your date of last insured or DLI. You must be found disabled prior to this date. If you worked consistently your DLI is usually 5 years after you stopped working.
Supplemental Security Income or SSI on the other hand is a needs based program and the funds come from the general tax revenues. SSI is for low income people who are aged blind or disabled. You must have less than $2,000 in resources or $3,000 if you are married. For more on SSI eligibility see my page on SSI.
To see tips on how to get disability benefits see my page "How to win Social Security Disability".