Folksonomies have shown interesting potential for improving information discovery and exploration. Recent folksonomy systems investigate on the use of tag assignments, which combine Web resources with annotations (tags), and the users that have created the annotations. In this paper, we investigate on the effect of grouping resources, i.e. creating sets of resources, and using this additional structure for search in folksonomies. Our experiments show that the quality of search result ranking can be significantly improved by introducing and exploiting the grouping of resources (onetailed t-Test, level of significance = 0.05). Categories and Subject Descriptors H.3.3 [Information Systems]: Information Search and Retrieval; H.4.m [Information Systems]: Miscellaneous; H.5.3 [Information Systems]: Information interfaces and presentationGroup and Organization Interfaces General Terms Social Search Keywords Social Media, Search, Ranking, Folksonomies, Web 2.0