Abstract. The evaluation of clustering algorithms is a field of PatternRecognition still open to extensive debate. Most quality measures found in the literature have been conceived to evaluate non-overlapping clusterings, even when most real-life problems are better modeled using overlapping clustering algorithms. A number of desirable conditions to be satisfied by quality measures used to evaluate clustering algorithms have been proposed, but measures fulfilling all conditions still fail to adequately handle several phenomena arising in overlapping clustering. In this paper, we focus on a particular case of such desirable conditions, which existing measures that fulfill previously enunciated conditions fail to satisfy. We propose a new evaluation measure that correctly handles the studied phenomenon for the case of overlapping clusterings, while still satisfying the previously existing conditions.