This thesis examines the general economic and intellectual climate of the mid-Tudor Commonwealth as a background for a specific study of the financial reforms instituted by Edward VI's government while the Duke of Northumberland controlled the Privy Council. The philosophy behind these measures parallels the principles expressed in A Discourse of the Commonweal of this Realm of England, a treatise written in 1549 by Sir Thomas Smith, Secretary to King Edward. In 1551-1552 the implementation of financial reform fell to Sir William Cecil, also King's Secretary and Northumberland's key administrator on the Council. In establishing the link between Smith's ideas and Cecil's policy, this thesis draws upon letters, Council records and Smith's written works to reveal the process by which thoughts became deeds in the mid-Tudor Commonwealth.