This dissertation examines three topics in macroeconomics. The first chapter studies the impact of severance payments on employment when firms can subcontract as a substitute for hiring workers. In countries with strict job security regulations firms use flexible staffing arrangements to buffer the regular workforce from economic fluctuations and avoid workers' firing costs. I set up a general equilibrium model in the tradition of Hopenhayn and Rogerson (1993) where firms can hire two types of workers: subcontractors that are totally flexible, and permanent workers that entail firing costs that increase with seniority in the job. Both types are perfect substitutes in production, but permanent workers are relatively less expensive as subcontractors' charges are higher than the firm's own production costs. I estimate the model using a simulated method of moments by fitting employment growth dynamics of Chilean manufacturing plants. I find that allowing firms to subcontract workers increases output, employment and productivity. This effect is stronger on output as subcontracted workers allow firms to respond more aggressively to productivity shocks, which enhances the allocation of labor across firms and hence total factor productivity (TFP). When firms can subcontract, the negative effects of firing costs are less than previously estimated in the literature. The second chapter analyzes the effects of capital adjustment costs on quantity dynamics and asset prices in a real business cycle model when the representative agent has Epstein-Zin preferences. Capital adjustment costs make it costly for agents to smooth fluctuations in consumption through the production sector, inducing them to take more consumption risk. I show this model accounts for the main statistical features of macroeconomic aggregate quantities. At the same time, adjustment costs increase the equity risk premium, with the mean stock return and its standard deviation in the order of magnitude consistent with the data. The model also produces a stable risk-free rate, and comes close to matching its average return. Finally, the third chapter (with Shuheng Lin) empirically examines the contribution of firm-level idiosyncratic shocks to aggregate fluctuations in the US, Germany, Canada, and the UK. We find shocks to large firms are of little relevance in the UK or Canada, but roughly explain one third of output fluctuations in the US and Germany. We argue the ability of the largest firms to transmit shocks is not universal, even when the firm size distribution is highly skewed as the theory suggests (Gabaix, 2011).