The aim of the studies included in this thesis has been to develop the knowledge about civil and military leadership processes and the conditions for these in situations characterized by extreme environmental demands.

The main part of the thesis is based upon empirical data gathered through semi-structured qualitative interviews with Swedish civil and military leaders. The studies, published in four articles, focused leadership during situations characterized by extreme environmental demands. The fourth article aimed at validating the theoretical model that was developed in study one. The thesis has pursued an integrated view in seeking to understand leadership and environment interactions during the conduct of international humanitarian aid and military peacekeeping operations. Hence it has been a matter of considering the individual leader in relation to the organisational and the external environment in order to study human adaption to meet the challenges and demands of disasters and conflicts.

The results show that leadership during international humanitarian aid and military peacekeeping operations is a highly complex and demanding task. Premises for the processes involve a great number of environmental factors. In order to restore system balance within a larger system, there has to be congruence between individual appraisal of the organizational and the external environment to achieve successful task completion. Inconsistency among the environmental factors influencing leadership processes may evoke adaptional struggles characterized by both positive and negative stress responses that may affect performance and task completion. Reappraisal processes are shown to involve continuous assimilation processes of, and accommodation processes to, the environment, illustrating the shifting balances between environmental forces, organizational pressures, and individual initiative.

 The findings on stress responses are in line with earlier research, demonstrating that stress reactions exhibit great similarities regardless of hierarchical level while also indicating a double-edged pattern concerning the overall development of stress reactions. However, it does seems that hierarchical differences exist with regard to moral stress, while moral stress appears to lack the double-edged pattern since no positive reactions are reported even at moderate levels of stress impact.

Taken together, future civil and military leaders need education in complex person-environment interactions in order to get a holistic picture of the underlying mechanisms, thus promoting the development of their adaptive capabilities.

It is suggested that this thesis can be regarded as a context-specific contribution to complex system theory by providing insight into the organizational and external environmental factors/demands that influence civil and military leadership.