This paper introduces multicriteria decision-aid methods for assigning alternatives topre-defined categories and develops a unified framework for preference aggregation methodsthat are based on concordance and non-discordance principles. Within this framework,we propose new multicriteria classification procedures based on non-totally compensatorymeasures of preference and similarity. We assume that the categories are given a priori andare characterised by fictitious alternatives serving as reference points, each representing atypical element of a category, or each representing a boundary between two categories.Several assignment methods are presented, all based on a filtering process exploiting binaryrelations constructed following the concordance and non-discordance principles. We firstconsider the case of ordered categories and a filtering procedure exploiting valued preferencerelations is proposed for assessing the membership of alternatives in categories. Then weconsider the case of non-ordered categories and filtering methods exploiting valued in-difference relations are introduced. Finally, a small example is given.