This study examines the effect on capital expenditures of “bonus depreciation,” which was intended to stimulate such spending by allowing businesses to immediately expense a portion of the cost of qualified capital expenditures from late 2001 through 2004. After controlling for many previously documented determinants of capital expenditures, some of our results indicate that capital expenditures during bonus depreciation’s availability were greater than those during the time it was not available, consistent with the expected effect. However, other results indicate that bonus depreciation had an insignificant effect on capital expenditures. These mixed findings generally persist through several sensitivity analyses. We interpret these results as weakly supportive evidence that Congress attained its goal of stimulating capital spending.