The thesis is based on two studies conducted on behalf of the Swedish Emergency Services Agency. One study focused on the problems associated with selection and training of future emergency directors in Sweden. The other study surveyed the emergency directors’ needs for decision support systems in major accidents. It was found that the demands on the person acting as an emergency director are severe. The leadership behaviour required in emergency management is quite different from that of the official in ordinary work settings. An emergency director is exposed to many stressors, such as information overload, time stress and especially during the initial stage of a major operation, an accumulation of subtasks. Decision-making is at the centre of emergency directors´tasks and competence, but the nature of decisions differ between minor and major operations. Decision-making in major operations imply distributed decision-making, DDM, in that decisions are distributed among many actors of which no single individual has complete knowledge of the current situation. Interview data confirmed some findings of previous DDM laboratory research. Perceived stressors are mainly associated to the initial phase of an operation. Information needs differ according to the decision-maker’s position in the distributed system. The key problems identified in both studies concern differences in skills and decision style required in major operations as opposed to minor operations. Few people have substantial experiences of acting in major operations. By relating data obtained in the studies to contemporary theoretical frameworks in decision-making research this thesis aims to propose a viable approach for addressing these problems.It is argued that the psychological dimension of the emergency director has to be considered as well as the contextual demands. An ecological approach is discussed that takes both the psychological processes and the task characteristics into account.