I was the Guru of rr retirement when working for the D&SNG .I helped guys sign up (much to the chagrin of A.Mouse). It works like this : If you work 120 months ,you are vested ,you can draw rr, Retirement instead of social security . If you work 240 or 360 months ,you get more money .If you drew on rr retirement unemployment insurance a lot of winters (like I did) ,you draw less at retirement .If you work for someone later who does not pay rr retirement ,your money gets dumped into your social security account . Since rr retirement has one of the best trust funds in the U.S.Government , politicians tried for years to abolish it ,and dump its funds into the ailing Social Security trust fund . The pressure was real high during the Reagan-Bush years .The unions ,however ,prevailed in protecting it . Though I am vested in rr retirement ,I doubt that there is much in my account ,so like a lot of o hers ,might be better off with Social Security (if there is such a fund September 1 ,2018 ,when I turn 65). Right wing congressmen want to get rid of such funds ,or gut them . They get a fat pension for serving just one term in Congress .You can thank them on your 65th birthday if such funds are memories .