Still research on strategizing activities and practices in the family business context is scant. At the same time there is suggested that entrepreneurial capabilities could be a useful concept to advance the study of strategizing in family firms, and corporate venturing in particular. In this paper we explore how family firm actors build entrepreneurial capabilities through strategizing activities to support their corporate venturing activities. We pay particular attention to the role of family owners/founders as core strategic actors emphasizing the importance of their resources to envision and mobilize activities needed to build these capabilities. Based on two case studies we found that entrepreneurial capabilities of performing activities for opportunity refinement, resource mobilization and customer orientation are needed to successfully launch, create and sustain new ventures.