Today, most enterprises are increasingly reliant on information technology to carry out their operations. This also entails an increasing need for cyber situational awareness—roughly, to know what is going on in the cyber domain, and thus be able to adequately respond to events such as attacks or accidents. This chapter argues that cyber situational awareness is best understood by combining three complementary points of view: the technological, the socio-cognitive, and the organizational perspectives. In addition, the chapter investigates the prospects for reasoning about adversarial actions. This part also reports on a small empirical investigation where participants in the Locked Shields cyber defense exercise were interviewed about their information needs with respect to threat actors. The chapter is concluded with a discussion regarding important challenges to be addressed along with suggestions for further research.