The invention relates to an assessment method for assessing acceleration behaviour of a driver of a vehicle. The method comprises determining the vehicles acceleration a, calculating one or more threshold values for its acceleration which depend on at least one situation-specific parameter, comparing its acceleration a with said one or more threshold values, and generating on the basis of the comparison a grading signal related to said calculated one or more threshold values. The invention relates also to an assessment system for assessing acceleration behaviour of a driver of a vehicle.