A number of options have been proposed to address the expected financing shortfall of Social Security in the next century. Most basic aspects of the various reform proposals are captured by the three options offered by the Advisory Council on Social Security in 1996. Common to all three options is that they would permit either public or private equity investment. This article discusses the economic risks involved in public and private equity investments as a funding solution for Social Security. To quantify the risks involved in equity investment, stochastic simulations are based on the economic assumptions of the 1998 Trustees Report of Old Age and Survivors Insurance and Disability Insurance in combination with different assumptions about the rates of return on bonds and stocks. For public equity investment, financial market risk remains significant for at least 40 years. For individual accounts, I find that the chance of doing worse than with Social Security or of falling into poverty in retirement is generally high, yet varies with income level, gender, family status, and employment history. In general, women, married workers with dependent spouses, or workers with incomplete work histories fare worse than men, single workers, or workers with complete work histories when compared either to the current system or to the poverty line. © 2000 by the Association for Public Policy and Management.