The effectiveness of different strategies of coping and the impact of coping diversity were tested under traumatic stress conditions. Participants were 632 U.S. soldiers stationed in Iraq (mean age = 27.7, 98% male). Results indicate that four of nine functional coping strategies (including some emotion-focused coping) as defined by the COPE scale were inversely related to psychological symptom, whereas five of six dysfunctional strategies were positively related. Overall, in comparison to the norm group, soldiers showed a depressed level of functional coping strategies. Hierarchical regression, used to control for demographics and coping strategy intercorrelations, indicated that positive reinterpretation, emotional social support, and humor were most strongly related to lower psychological symptoms, whereas venting emotions, denial, mental disengagement, behavioral disengagement, and alcohol and drug use were related to higher levels of psychological symptoms. Two indices of coping diversity were tested. The index more strongly related to higher psychological adjustment was the sum of deviations from the mean of specific coping strategies combined with the alignment of functional and dysfunctional strategy clusters. Implications for research and application were discussed.