The era of monetary targeting ignited research into the area of interest rate response to money supply announcements. During the 1980s and 1990s, research focused in this area; however, there is been a lack of updated research. This study examines the updated response of interest rates to unanticipated changes in Ml money supply announcements for the sample period 1985 to 2005. The crucial ideas behind this hypothesis include money demand, money supply, expectations, and the role the Federal Reserve plays in the interaction of the three. Data was taken from the Federal Reserves statistical and historical data release for weekly M1 money supply measures and for daily interest rates of treasury securities. The results revealed an inability of the presented model to capture the relationship between money supply announcements and interest rates; leading to the conclusion of a mis-specified model.