The aim of this research is to achieve a better understanding of the processes underlying knowledge transfer (KT) in Social Sciences and Humanities (SSH). The paper addresses: first, the extent of SSH research groups' engagement in KT and the formal KT activities used to interact with non-academic communities; and second, how the characteristics of research groups may influence engagement in various types of KT. The empirical analysis is at research group level using data derived from a questionnaire of SSH research groups conducted by the Spanish Council for Scientific Research (CSIC). We find that KT activities are based on relational rather than commercial activities. The most frequent relational activities in which SSH research groups engage are consultancy and contract research, with personnel mobility a marginal activity. We find also that the characteristics of research groups (e.g. size and multidisciplinarity) and individuals (e.g. status and research impact) are associated with involvement in KT activities and that a deliberate focus on the societal impacts and relevance of the research conducted is strongly related to active engagement of research groups in all the modes of KT considered in this study. From a managerial perspective, our findings suggest that measures promoting a focus on the societal impact of research could enhance research groups' engagement in KT activities.