The book presents original research of key interest rates – basic and on the interbank market – as an instrument to be stimulated the economic growth. The author uses Bernanke – Blinder model to develop the research by specific monetary conditions under the Currency Board. The design of this innovative book helps readers to understand the classical transmission mechanism of interest rate by the Currency Board. It researches the impact of key interest rates on the aggregate demand, thereby on the Gross domestic product by these conditions. The correlation is presented by the case of Bulgaria. The book suggests the researchers and professionals to distinguish the role of key interest rates as an instrument to realize the economic growth by the Central Bank and by the Currency Board and put in the practice this knowledge.