Abstract: The Web 2.0 maximizes Internet concept of encouraging its users to cooperate effectively for offer of virtual services and content organization. Among various potentialities of Web 2.0, folksonomy appears as a result of free attribution of tags to Web's resources by user himself. Folksonomies describe Web's resources; however, they aren't integrated in metadata in general. In order for them to be intelligible by machines and therefore used in Semantics Web context, they have to be automatically allocated to specific metadata elements. There are many metadata patterns. The focus of this investigation will be Dublin Core (DC) which is a gathering of metadata for description of electronic resources and which has been adopted by Institutional Repositories as a way of standardization and interoperability. We propose an investigation which intends to identify of metadata originated from folksonomies and integrate them in a DC Ontology extended so as to allow that values reported in tags may be conveniently gathered by protocol for metadata harvesting, specifically Open Archives Initiative - Protocol for Metadata Harvesting (OAI-PMH). This paper will present results of pilot study developed in beginning of investigation as well as metadata preliminarily defined. Metadata may be defined as a group of for description of resources [1]. There are many standards of metadata, however, in repository context; we can point out Dublin Core Metadata Element Set (DCMES) or simply Dublin Core (DC) which is a metadata pattern for description of electronic resources. This standard is well diffused, used globally and on a broad scale due to some factors: a) it was created specifically for description of electronic elements; b) it has an initiative which is responsible for its development, maintenance and spreading, Dublin Core Metadata Initiative (DCMI); c) it is group of metadata used for protocol Open Archives Initiative - Protocol for Metadata Harvesting (OAI-PMH), a mechanism for data transfer between digital repositories. The insertion of metadata in repositories may be done by authors themselves, professionals who mediate deposit or of final users. The more active participation of users in construction and organization of Internet contents is result of evolution of technologies used in Web, so-called Web 2.0, it is 'the network as platform, spanning all connected devices; Web 2.0 applications are those that make most of intrinsic advantages of that platform: delivering software as a continually-updated service that gets better more people use it, consuming and remixing data from multiple sources, including individual users, while providing their own data and services in a form that allows remixing by others, creating network effects through an architecture of participation, and going beyond page metaphor of Web 1.0 to deliver rich user experiences.' [2]. Among possibilities of Web 2.0 Folksonomy comes up as the result of personal free tagging of and objects (anything with an URL) for one's own retrieval. The tagging is done in a social environment (shared and open to others). The act of tagging is done by person consuming information [3]. The tags which make up a folksonomy would be key-words, categories or metadata [4]. In this brief definition of tag, we can notice that when attributed by users they can represent different roles. In a study [5][6] following roles are pointed out: Identifying What (or Who) it is About, Identifying What it Is, Identifying Who Owns It, Refining Categories, Identifying Qualities or Characteristics, Self Reference and Task Organizing. In another study, Kinds of Tags (KoT), which compared tags with DC metadata elements, authors observed that there are some tags which cannot be inserted in any of already existing and therefore, concluded that other metadata may be defined in order to include descriptions arising from folksonomies. Some probable which were identified: Action_Towards_Resource, To_Be_Used_In, Rate e Depth [7][8]. The KoT is being developed in partnership with following universities: Universidade do Minho (Portugal), University of Bologna (Italy), UKOLN (United Kingdom), Universidad Carlos III (Spain), La Trobe University (Australia) and Universit? Libr? de Bruxelles -Facult? de Philosophie et Lettres (Belgium) and has objective of verifying how tags derived from folksonomies can be normalized aiming at their interoperability with metadata standards, specifically DC. Summing up, metadata are groups of for description of digital resources, holding different standards, among them DC which is adopted by Repositories as basis for protocol for metadata harvesting (o OAI-PMH). In Web 2.0 context, folksonomies arise, which are result of Web resource tagging by its own users. Tags are a complementary form of description which expresses user's view of resource being used. It can be observed through preliminary results of KoT project that current of description defined in DCMI Metadata Terms do not include all descriptive attributed by resource users by means of these tags. In context shown, giving continuity to analysis resulting from KoT project, we propose an investigation which aims at identifying metadata derived from folksonomies and integrate them in a DC Ontology extended so as to enable that values reported in tags may be conveniently gathered by protocol for metadata harvesting. Being so, we intend to develop a qualitative approach research and answer following questions: Q1 - Which metadata are necessary to contain folksonomy values?; Q2 - Which metadata should be created and which is their relation with already existing ones in Dublin Core?; Q3 - Which codification schemes should be used and what is their relation to already recommended by DCMI?; Q4 - Which Ontology related to DC already enable access to previously established conceptualizations? Q5 - Accomplishing what is stipulated in DCAM, what is extension of DC Ontology which should be made available openly? The procedures are divided in four stages: 1) Analysing tags contained in KoT project dataset- at this stage we will analyse all tags in relation to resources to which they have been attributed. Complementarily, to settle doubts, it will be necessary to turn to lexical resources (dictionaries, encyclopaedias, Word Net, Wikipedia, etc) and to analyse tags in relation to its users to understand functionality of tag attributed as a metadata element. At this stage a pilot study will be developed to refine methodology proposed to verify if variants proposed for grouping and analysing tags are adequate to identify probable new metadata elements which could be extracted from folksonomies. 2) Propose complementary metadata to DC - Establishing description originated from folksonomies based on DC standard, DCAM model, ISO Standard 15836-2003 and NISO Standard Z39.85-2007 norms. At this stage we intend to propose and/or qualifiers complementary to DC. 3) Forming an Ontology - Here we intend to fulfil Integration of DC Ontologies with and/or qualifiers derived from folksonomies. The ontology will be created from Prot?g? tool and coded in OWL. 4) Validation of proposal - carried out by scientific community as methodology and results obtained will be presented in relevant events and scientific magazines and by DCMI Social Tagging community through investigations via online questionnaires and workshops proposed to community. It is intended that results of research may provide support so that applications based on Artificial Intelligence permit automation of harvesting processes including description provided from folksonomies. This paper will present results of pilot study (that is being finalized) alongside with preliminary results of first research stage: tag analysis. This stage will be done in following phases: a) Analysis and grouping of tags in their variant forms; b) Analysis of tags in relation to DC metadata and its qualifiers. The preliminary results of KoT point to possible proposal of some metadata or element refinements to DCMI. Those terms will potentially accommodate tags that currently do not have a metadata holder. The results of this research will therefore allow to determinate if KoT preliminary findings are verified and in which extension. The final paper will conclude with this discussion.