Police officers are regularly exposed to traumatic events. However, the psychological response to this exposure, even when examined in relation to a single incident, typically shows considerable variability (Paton & Violanti, 1996; Violanti, Paton & Dunning, 2000). Some of this variability can be attributed to differences in the event characteristics officers encounter (Schmuckler, 2004), and some will emanate from the individual, team and organizational factors associated with the psychological response to a discordant experience. If the factors that influence this variability can be identified, it may be possible to alter them in ways that mitigate officers’ traumatic stress risk. This chapter takes as its starting point the position that traumatic stress should be conceptualized in terms of the risk of developing adverse outcomes, rather than the latter being assumed to be a fait accompli of critical incident exposure.