The level (or scale) at which social capital can be conceptualised and measured ranges potentially from the macro-level (regional or country level), to the mesolevel (neighbourhoods, workplaces, schools), down to the individual level. However, one glaring gap in the conceptualisation of social capital within the empirical literature has been the level of the family. Our aim in this review is to examine the family as the ‘missing level’ in studies on social capital and health. To do so, we conducted a systematic review on the use and measurement of this notion in the health literature, with the final intention of articulating a direction for future research in the field. Our findings are consistent with the notion that family social capital is multidimensional and that its components have distinct effects on health outcomes. Further investigation is needed to understand the mechanisms through which family social capital is related to health, as well as determining the most valid ways to measure family social capital.