In the current society, universities and research centers have acquired an important role as agents responsible for knowledge transfer (KT) to the non-academic environment (OCDE, 1996). The different ways in which these collaborations take place have been the subject of many conceptual (Molas-Gallart et al., 2002) and empirical studies (D'Este and Patel, 2007; Landry et al., 2007) in recent years. Many authors have adopted a perspective for analyzing knowledge transfer activities at the level of the university or individual researcher, even if the form of organization in the scientific system is increasingly the research group (Hernández et al., 2009). KT literature has concentrated in the results generated in experimental science disciplines whereas KT in Humanities and Social Sciences (HSS) research has been scarce (Castro-Martínez et al., 2008). Under these considerations, the aim of this paper is to contribute to KT literature from an area of study generally neglected (HSS) and a perspective (research group) that have received less attention. Thus, the questions addressed in this study are: What are the main mechanisms of KT used by HSS research groups to collaborate with non-academic agents? 2) What are the determinants of these collaborations? The sample of this study is made up of 79 research groups comprising more than 80% of the population belonging to the HSS area of the Spanish Council for Scientific Research (CSIC), the most important public research organization in Spain. The data were gathered in two phases. In the first phase, between May 2006 and March 2007, two instruments were used for the collection: a) semi-structured face-to-face interview with a representative of each research group identified; b) a questionnaire based on Bozeman?s dimension of KT (Bozeman, 2000). The second phase took place in September 2010 by obtaining data related to the leader characteristics from the CSIC corporative database and the ISI Web of Knowledge. The results show that HSS research groups are very active in some KT activities such as technical advice, consultancy and contract research, whereas their involvement in personal mobility activities is low. Logistic regression analysis shows that the likelihood that researcher groups engage in any KT mechanism is not explained by the same factors. However, we obtain evidence showing that there is a common variable positively related with the engagement of HSS research groups across the different mechanisms analyzed: the focus on the social utility of the research.