The Enron bankruptcy has focused media attention on stock market losses suffered by Enron employees. Recent revelations indicate that Enron executives -- despite knowledge of their firm's shaky financial situation -- encouraged employees to hold Enron stock in their tax-subsidized 401(k) retirement accounts. Many employees lost the bulk of their retirement savings as a result.

Less attention has been paid to the fact that as Enron employees lose their jobs, their other employer-provided benefits -- such as health insurance -- are also at risk. Indeed, employees at any firm -- whether properly managed or not -- risk losing benefits if they are laid off or if the firm goes bankrupt. Moreover, employers have great latitude to change their benefit policies or to terminate benefit programs. Benefits can be here today, gone tomorrow.

So, are there any benefits not at risk for Enron or other employees? The most important is Social Security, which provides pension, disability and retiree health care to most American workers. Employees who are laid off and find jobs elsewhere take their Social Security eligibility with them. Employers do not determine Social Security benefit policies -- that is left to Congress. Social Security, in short, is portable from job to job and unaffected by the fate or actions of any one company.

The Enron saga thus points to a larger lesson. America's social welfare system was built up soon after World War II on the basis of tax incentives to employers. Employers were thereby encouraged to provide company-by-company benefits. These tax incentives have become among the most costly to the federal Treasury. Yet the postwar system was premised on an employment relationship that no longer is relevant: a male breadwinner working an entire career for a large employer. If the breadwinner were a professional or managerial employee, it was assumed that the employer would take a paternal interest in his welfare. If he were a blue-collar worker, it was assumed that a union contract would protect him.

Today, few professional and managerial employees expect to work 30-40 years at a single firm. And unionization in the private sector has fallen below 10% of the workforce. All workers must worry about the impact of job mobility, company bankruptcy or changes in job-based benefits.

Given these changes, social welfare concerns -- pension, health care, life and supplementary disability insurance -- ought not to remain the responsibility of employers. While Social Security will need reforms as baby boomers near retirement, it must retain a central role in national retirement policy. Individual saving accounts -- independent of any one employer -- are another important element. More complicated, but no less essential, is the creation of a core health insurance system that is portable from job to job.

And what about the job-based stock ownership and stock option plans that were the rage of the '90s and figured so prominently in the Enron fiasco? If employers want to subsidize such plans on the assumption that they enhance employee motivation, they can continue to do so. But stock-based incentive plans have little to do with retirement and should not continue to enjoy tax subsidies.

Mitchell is Ho-su Wu Professor at The Anderson School and School of Public Policy and Social Research.