Employing a comprehensive database on transactions of commercial paper issued by domestic U.S. nonfinancial corporations, we study the determinants of very short‐term corporate yield spreads. We find that liquidity plays a role in the determination of spreads but, somewhat surprisingly, credit quality is the more important determinant of spreads, even at horizons of less than 1 month. These results are robust across a variety of proxies for liquidity and credit risk, and have important implications for the literature on the modeling of corporate bond prices.