In this paper, the author uses structural vector autoregression methodology to decompose U.S. nominal interest rates into an expected inflation component and an ex ante real interest rate component. He identifies inflation expectations and ex ante real interest rate shocks by assuming that nominal interest rates and inflation expectations move one-for-one in the long-run—they are cointegrated (1,1)—and that the real interest rate is stationary. He finds that changes in inflation expectations and in the ex ante real interest rate are both important in explaining fluctuations in the U.S. 1-year and 10-year government bond rates. The author also finds that, while the increase in the 1-year and the 10-year bond rates in the 1970s and the early 1980s mainly reflects higher inflation expectations, changes in ex ante real interest rates appear to account for most of the fluctuations in these rates in 1994 and in the first half of 1995.