Cutting cost-of-living adjustments (COLAs) is often proposed as a way to limit Social Security costs, which will soar as the nation ages. This brief shows, however, that even modest COLA reductions would lead to substantial cuts in family income for the oldest and poorest retirees. Trimming COLAs to one-half of a percentage point below the annual percentage change in the Consumer Price Index, for example, would reduce median Social Security benefits in 2040 by 13 percent for adults ages 85 and older, and would push an additional 2 million older adults onto the bottom rungs of the income distribution.