The purpose of this article is to identify the various schools of management theory, indicate the source of the differences, and to provide some suggestions for disentangling the management theory jungle. Koontz describes six schools of management theory as follows. 1. The Management Process School, 2. The Empirical School, 3. The Human Behavior School, 4. The Social System School, 5. The Decision Theory School, 6. The Mathematical School. The Major Sources of Mental Entanglement that create the Management Theory Jungle. Five sources of entanglement or confusion include the following: 1. The Semantics Jungle - There is no agreement on the meaning of the words management, organization, leadership, communication, and human relations to give a few examples. 2. Differences in the Definition of Management as a Body of Knowledge - What is management? Who is a manager? If everything is management and everyone is a manager, how can management theory be regarded as a useful or scientific? 3. The a priori Assumption - Ignoring the work of Fayol, Mooney, Brown, Urwick, Gulick and others on the grounds that they are universalists. 4. The Misunderstanding of Principles - For example, confusion over the validity of principles such as unity of command, and span of control. 5. The Inability or Unwillingness of Management Theorists to Understand each other - The roadblock to understanding is unwillingness.