In this paper, we first employ the well known Cover-Coefficient Based Clustering Methodology (C3M) for clustering XML documents. Next, we apply index pruning techniques from the literature to reduce the size of the document vectors. Our experiments show that for certain cases, it is possible to prune up to 70% of the collection (or, more specifically, underlying document vectors) and still generate a clustering structure that yields the same quality with that of the original collection, in terms of a set of evaluation metrics. © 2010 Springer-Verlag Berlin Heidelberg.