This essay focuses on the relevance of family relationships (conceived as familial social capital) to the common good (conceived as public social capital). The article consists of three sections. The first is an attempt to discover why some prominent social capital theories do not consider family ties a specific form of social capital; in fact, modernist ideology (particularly widespread in Italy) tends to exclude them from the scientific debate. The second section outlines a concept of familial social capital based on relational variables as has been used in Italian empirical research to show the scientific usefulness of reintroducing family ties into the social capital. The third section summarises the results of some empirical studies on family relationships as fostering the wellbeing of family members and the development of communitarian, associative and generalised social capital too. The conclusion underlines the importance of familial ties in transmitting civic virtues, reciprocity, and trusting attitudes from (some forms of) family to the wider society.