U.S. output has expanded only slowly since the recession trough in 2009, even though the unemployment rate has essentially returned to a pre-crisis, normal level. We use a growthaccounting decomposition to explore explanations for the output shortfall, giving full treatment to cyclical effects that, given the depth of the recession, should have implied unusually fast growth. We find that the growth shortfall has almost entirely reflected two factors: the slow growth of total factor productivity, and the decline in labor force participation. Both factors reflect powerful adverse forces that are largely unrelated to the financial crisis and recession-and that were in play before the recession.A data appendix is available at http://www.nber.org/data-appendix/w23543Under standard growth theory, slower TFP growth and falling participation should raise the capital-output ratio, since less investment is needed simply to keep pace with technology and the labor force. This higher capital-output ratio reduces the marginal product of capital and lowers the equilibrium real interest rate. By 2016, the cyclically-adjusted capital-output ratio had returned to its trend growth path, but not above that path as growth theory would suggest.Possibly, additional capital deepening lies ahead. Or, other factors might have depressed the steady-state capital-output ratio. Gutierrez and Philippon (2016) argue that investment has been held back by rising market power, which lowers the marginal revenue product of capital and thus discourages capital formation. Alexander and Eberly (2016) attribute part of the decline in investment to the relocation of capital-intensive manufacturing industries outside the U.S. Importantly, neither of these hypotheses is obviously related to the recession.Although our account leaves little room for demand-side explanations of persistently slow growth, we do investigate demand-side forces. Two quantitatively important factors are the unusually slow growth of federal government purchases during 2012 through 2014, which we associate in part with the sequester; and the delay in the usual rebound of state and local government purchases, which we associate with the housing market collapse and the financial crisis. Absent such delays, output growth would have been higher early in the recovery. The black line in Figure 1 would have intersected the red line sooner, implying less cumulative loss in output (and employment). But, looking over the entire recovery, the seeds of the disappointing growth in output were sown prior to the recession in the form of a declining participation rate and slow TFP growth. Indeed, the scaling back of consumption and investment plans in response to slowing TFP growth could induce its own recessionary pressures beyond those from the financial crisis alone. Blanchard, Lorenzoni, and L'Huillier (2017) show that this effect could be large, especially with interest rates at the zero lower bound.Turning now to the details of our analysis, we use counterfactual "cyclically adjusted" paths t...