A more intuitive, easy and powerful representation, access, and retrieval of information is nowadays a necessary feature of information systems that have become a common instrument for a wide class of users in di?erent areas and for the most diversi?ed tasks. The management of imprecision and uncertainty in databases has become an important research area, which has known an impressive growth. This is testi?ed the increasing number of special sessions in international conferences and workshops devoted to this theme. Generally, this topic matured and developed independently within both the traditional database community and the community of researchers on fuzzy sets, and only very recently some joint initiatives have been undertaken. Since the Workshop titled “Supporting Imprecision and Uncertainty in Flexible DataBases” we organized within the DEXA Conference in Zaragoza on August 2004, our intent is to bring together a wide community of - searchers in the ?eld of databases, Information Retrieval, Spatial Information Systems, knowledge representation and multimedia, to share experiences and methods concerning the management of uncertainty and imprecision in da- bases. This volume collects a selected number of contributions of well known pioneerresearcheswho,atvariouslevels,proposedmodelsandtheapplication ofmethodstorepresentandmanageuncertaintyandimprecisionindatabases. Many approaches have been proposed in the literature on the modelling of uncertainty and imprecision in databases. To o?er a panoramic view of the methods proposed so far to students, researchers and insightful practitioners, we included in the volume survey chapters on classic topics such as ?exible querying in databases, and database models to represent imperfect data.