The specific eligibility requirements for Social Security benefits vary depending on the type of benefits, the age of the person filing the claim and, if you are claiming as a dependent or survivor, the age of the worker.
There is one general requirement, however, that applies to all Social Security programs except for SSI (Supplemental Security Income): The worker on whose earnings record the benefit is to be paid must have worked in "covered employment" for a sufficient number of years. This means that the worker must have earned enough of what Social Security calls "work credits" by the time he or she claims retirement benefits, becomes disabled, or dies (usually a total of at least ten years of work).
For Social Security retirement benefits, you must be between the ages of 62 and 70 to start collecting benefits.
To check on your eligibility, see Nolo's article Checking you Social Security Earnings and Benefits or call the Social Security Administration at 800-772-1213.