Abstract: This paper addresses the question "what is the Science of Command and Control (C2)?" by first defining the three key perspectives that cover that which comprises C2, and by examining the system-level properties of these three perspectives in combination. The paper then analyses the concept of a 'science' of C2 by extracting the core components of a science: an organised body of knowledge and the process of acquiring that body of knowledge. In addition to these, the paper recognises the role that the application of the 'science' plays in advancing the state of understanding of C2. The paper then uses the definition of the science of C2 to formulate a general matrix for understanding C2 research programs. The paper closes by studying examples of extant research placed in this matrix. The result is a comprehensive definition of the science of C2 and a tool for understanding C2 research.