The Swedish Armed Forces have to decrease the number of officers in the near future as a consequence of the increased participation in international missions and a reduced ground organisation. The need of officers with different grades, in different ages and with different competences will be changed. To perform the transformation of the personnel system from today´s structure to future needs, the Armed Forces have to take intended actions. The consequences of such actions can be studied with simulation models. This report presents seven different models that each describes one specific perspective of the personnel mainenance. Together the models elucidate a larger area. The models handle large populations. Small personnel groups, such as helicopter pilots, have to be handled separately. To find appropriate actions for transforming the personnel systems, it is necessary that the Armed Forces decide what it strives towards in a ten years perspective. In the report, we discuss what kind of factors, soft and hard, that have to be considered. One aim has been to point out which questions can be answered with simulation models and which questions must be handled separately. Another overall aim of the work presented have been to evaluate the use of simulation models in the area of operational research as it is carried out today at FOI.