Previous studies have shown that car seat properties play an important role for the occupant protection during various types of accidents. An improved understanding of the interaction between the occupant and the seat is therefore desirable, since this could lead to enhanced protective capacities of future car seats.In this work a test-rig has been developed and constructed, by means of which it is possible to study the response from various seats during frontal collisions. With small modifications the test-rig can be utilized to study other collision directions as well.The rig has been used in a test series, which comprises four car seats in altogether 14 tests. In order to evaluate the interaction between the seat and the dummy, measurements have been made on: the seat frame; the floor connections; the seat belt; the submarine-beam; and on several locations in the dummy.Due to the complexity of the dynamic interaction between the seat and the dummy, the process will be transferred into the mathematical model MADYMO3D, since this model allows for calculations of parameters that are not possible to measure in the experiments. The mathematical model will also be used to establish the characteristics of a seat that is optimal with respect to safety properties and comfort aspects.