In this paper we develop a theory of women’s participation in the angel investment market. First, women may have a lower propensity for risk and a more conservative attitude to investment, reflected in different patterns of investment activity. Second, the homophily principle, that similarity breeds connection, structures network ties of every type: as women are in different social networks than men and as a result have different access to social capital, their investment activity will differ. Third, research into competition and performance in heteronormative environments suggests that women perform less well than in single-sex environments, which would be reflected in lower participation in angel investing through mixed-sex groups. Fourth, there may be a ‘glass wall’ effect: for women: less diverse career tracks and lower levels of entrepreneurial backgrounds will be reflected in lower investment levels.