Focusing on both hiring and firing margins, this paper revisits effects of fiscal expansion on unemployment. We provide evidence that an increase in government spending increases the job finding rate and reduces the separation rate, lowering unemployment in the U.S. by using a structural VAR model. We then develop a DSGE model with search frictions where job separation is endogenously determined. Our model can capture the empirical pattern of responses of the job finding, separation, and unemployment rates to a government spending shock. We also demonstrate that model's predictions are in contrast with earlier studies that assume exogenous separation.