In this paper we present a contribution of Multicriteria Decision Analysis to the evaluation of Animal Welfare in European farms. We present the main features of the overall evaluation process designed to assess animal welfare on a farm from measures taken on the animals or their environment. We review the main steps of the construction of subcriteria and criteria. Then we discuss the aggregation problem and the design of a multicriteria sorting procedure to assess overall welfare from those criteria. This study is illustrated on cattle but is designed to be transposed to other animal species (e.g. pigs, poultry) so as to provide a general evaluation system for animal welfare on farms.