There has been an increasing integration of civilian and military actors in multinational peace support operations. The aim of this study is to describe and analyse this trend. In the first part, concepts for peace support operations and civil-military cooperation is studied. The second part is a study of the NATO-led peace support operation in Afghanistan. There is a Swedish perspective throughout the report. The concepts studied in the report show that there now is a more comprehensive approach to conflicts and the tools available to solve them. But as the second part in the report shows, it is still difficult to implement this new approach. A number of recommendations for more efficient civil-military cooperation are made in the report. The recommendations are primarily intended for the Swedish Armed Forces but might also be interesting for other actors working with peace and security.