This research was supported by grants from the National Institute On Aging of the National Institutes of Health under award numbers R01 AG060104 and R01AG053396. This paper was prepared for the Annual Review of Economics htts://doi.org/10.1 146/annurev- economics-051520-015607 The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications. ◎2021 by Anne Case and Angus Deaton. All rights reserved. Short sections of text, not to exceed two paragraphs, may be quoted without explicit permission provided that full credit, including◎notice, is given to the source.