GRI reporting was created with a dual purpose: on one hand, to grow awareness for the entities, regarding the importance of their involvement in environmental, social and economic activities, and on the other hand, to answer to the need of transparency of stakeholders in decision-making process. For this reason, in 2010, non-profit organizations have begun to upload their reports on the GRI website, pointing out that their activities fall within the social side of society, perhaps more than the case of economic organizations. The cognitive approach starts with the presentation of six versions published by this institution, as a response to the necessity to identify indicators with an increased degree of relevance, comparability and verifiability. Subsequently, by accessing the GRI database for the period 2010-2015 and with reference to the European area, a classification of non-profit organizations was considered, at international and European level. In order to present the importance of  the GRI reports, the paper presents the progress of these organizations, in presenting their voluntary activities according to GRI versions which were applicable at the time and types of certifications of  their published data (A, A +, B, B +, C, C +, in accordance-core and in accordance-comprehensive).