We thank Sinem Buber, Mita Goldar and Matthew Levin from ADP for their support on the project. We also thank Steve Davis, Jan Eberly and Jonathan Parker for comments on prior drafts. As part of the University of Chicago data use contract, ADP reviewed the paper prior to distribution with the sole focus of making sure that the paper did not release information that would compromise the privacy of their clients or reveal proprietary information about the ADP business model. The views expressed in the paper are the authors' and do not necessarily reflect the views of ADP or the National Bureau of Economic Research. Additionally, the analysis and conclusions set forth here are those of the authors and do not indicate concurrence by other members of the research staff or the Board of Governors. At least one co-author has disclosed a financial relationship of potential relevance for this research. Further information is available online at http://www.nber.org/papers/w27159.ack NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

Since 2007, the labor force participation rate has fallen from about 66 percent to about 63 percent. The sources of this decline have been widely debated among academics and policymakers, with some arguing that the participation rate is depressed due to weak labor demand while others argue that the decline was inevitable due to structural forces such as the aging of the population. In this paper, we use a variety of approaches to assess reasons for the decline in participation. Although these approaches yield somewhat different estimates of the extent to which the recent decline in participation refl ects cyclical weakness rather than structural factors, our overall assessment is that much-but not all-of the decline in the labor force participation rate since 2007 is structural in nature. As a result, while we see some of the current low level of the participation rate as indicative of labor market slack, we do not expect the participation rate to show a substantial increase from current levels as labor market conditions continue to improve.JEL Codes: E24, E32, E66, J21, J26.Keywords: Labor force participation, retirement behavior, disability insurance, implications of an aging population, youth employment, labor market slack, labor market fl uctuations and the business cycle.

Since 2007, the labor force participation rate has fallen from about 66 percent to about 63 percent. The sources of this decline have been widely debated among academics and policymakers, with some arguing that the participation rate is depressed due to weak labor demand while others argue that the decline was inevitable due to structural forces such as the aging of the population. In this paper, we use a variety of approaches to assess reasons for the decline in participation. Although these approaches yield somewhat different estimates of the extent to which the recent decline in participation reflects cyclical weakness rather than structural factors, our overall assessment is that much of the decline is structural in nature. As a result, while we believe some of the participation rate's current low level is indicative of labor market slack, we do not expect the rate to substantially increase from current levels as labor market conditions continue to improve.

Many traditional official statistics are not suitable for measuring high-frequency developments that evolve over the course of weeks, not months. In this paper, we track the labor market effects of the COVID-19 pandemic with weekly payroll employment series based on microdata from ADP. These data are available essentially in real-time, and allow us to track both aggregate and industry effects. Cumulative losses in paid employment through April 4 are currently estimated at 18 million; just during the two weeks between March 14 and March 28 the U.S. economy lost about 13 million paid jobs. For comparison, during the entire Great Recession less than 9 million private payroll employment jobs were lost. In the current crisis, the most affected sector is leisure and hospitality, which has so far lost or furloughed about 30 percent of employment, or roughly 4 million jobs.

Why do more educated workers experience lower unemployment rates and lower employment volatility? A closer look at the data reveals that these workers have similar job finding rates, but much lower and less volatile separation rates than their less educated peers. We argue that on-the-job training, being complementary to formal education, is the reason for this pattern. Using a search and matching model with endogenous separations, we show that investments in match-specific human capital reduce the outside option of workers, implying less incentives to separate. The model generates unemployment dynamics that are quantitatively consistent with the cross-sectional empirical patterns.