For people born between 1943 and 1954, the full retirement age is 66. The full retirement age increases gradually, beginning with people born in 1955. So for someone born in 1955, full retirement age is 66 and two months; for someone born in 1956, it's 66 and four months. For people born in 1960 or later, full retirement age is 67.
To see where you fit in, use this table from the Social Security Administration.
Published August 1, 2011