Information complexity and expanse of cybersecurity space surpasses the cognitive ability of individual analysts to be truly situationally aware. Team level situation awareness in cyber security can be described as the coordinated perception and comprehension of significant events in the network by all team members that serve as the basis for effective response actions. Effective teamwork is imperative to transform individual analysts’ disparate cognition and situation awareness into team level, collective cognition and situation awareness. We employed a hybrid methodology that makes opportunistic use of a mix of field observations, simulation, modeling, and laboratory experimentation to study and improve team situation awareness in the cyber security domain. Findings from experiments summarized in this chapter demonstrate the important role of teamwork at every level of cyber security defense and the detrimental effect of team process loss on overall cyber defense performance.