Until recently, the “three-legged stool” was the reigning metaphor for achieving retirement security. Workers could anticipate being supported as they aged by a combination of Social Security benefits, private pension income, and personal savings. This model no longer holds. Traditional pensions have almost disappeared from the private workforce, personal savings are low, and Social Security benefits face political and actuarial threats. The new model relies on defined contribution (“DC”) plans like the 401(k).