Background -- The Approach -- Theory of Real Systems -- Theory of System Knowledge -- The Intelligent Enterprise -- Realizing Enterprise Intelligence -- Conclusion.Today's enterprises have to continuously extend their operational limits to earn profit, thrive and prosper. Over time evolution led to the development of two concepts to master this challenge: intelligence and knowledge. This work introduces a system theoretic perspective on enterprises, regarding them as natural living systems formed by evolutional forces. Intelligence and knowledge manifest in the system's behavior. 'Intelligence' is identified as the necessary framework that realizes continuous adaptation through the ongoing development and incorporation of control procedures and building blocks. The content that fills this framework is the 'Enterprise Knowledge'. The rigid framework of business processes has to be replaced by a project framework, employees have to be integrated as 'Knowledge Workers' and IT systems have to offer advanced structural and organizational properties to facilitate declarative processing. "The transition towards intelligent enterprises requires drastic organizational changes. ... With the presented work Markus Thannhuber introduces a theoretic framework and opens up new perspectives for Managerial Sciences, Organization Theory and Industrial Engineering." Hans-Jörg Bullinger, President of the Fraunhofer-Gesellschaft, Munich, Germany .