Mass-selected W cluster anions in the size range of 20–3500 are deposited on highly ordered pyrolytic graphite (HOPG) surfaces. The structures of resulting thin films are studied using atomic force microscopy. Clusters with more than ∼600 atoms form thin films, in which the clusters are not completely merged but survive as individual species to a certain extent. The new class of materials fabricated here (cluster-assemblies) has a potential for applications in heterogeneous catalysis and in optoelectronic devices. In addition, they are interesting from the perspective of basic research.