The correspondence prompted by McKenzie et al's (Reference McKenzie, Whitley and Weich2002) editorial suggests that social capital can be the property of individuals as well as groups (Pevalin, 2003; Reference WalkupWalkup, 2003). However, McKenzie finds this idea problematic and argues that, as the majority of health scientists conceive of social capital as an ecological concept, we should ‘consider effects at an individual level as social networks’ (Reference McKenzieMcKenzie, 2003: p. 458). This restricted view rejects the potential contribution to psychiatric research of alternative sociological conceptions of social capital that are both rigorously defined and empirically tested.

One such approach is taken by Lin et al (Reference Lin, Cook and Burt2001) who adopt neo-Marxist notions of capital. Here, social capital is ‘investment in social relations by individuals through which they gain access to embedded resources to enhance expected returns of instrumental or expressive actions’ (Reference Lin, Cook and BurtLin et al, 2001: p. 17). Embedded resources may be collective assets, such as civic associations or social groups, or individual resources such as social support. Individuals have unequal access to social capital because of the strength of interpersonal ties or location within the social structure.

Inequality in access to social capital is hypothesised to produce unequal mental health gains. For example, the inability of a single mother to obtain childcare from her friends and family may increase her risk of depression (Reference Brown, Harris and HepworthBrown et al, 1995). Similarly, gaining employment through informal social contacts, as more than a third of the workforce does (Reference FlapFlap, 1999), may provide a positive life change and assist recovery from depression or other mental illnesses. Echoing Pevalin's (2003) views about Bourdieu's work, this approach to social capital is also dynamic and allows us to examine how access to social capital may influence the onset of and recovery from mental illness.

It is clear that there is a family of social capital theories, each measuring slightly different constructs. We do not feel that it is helpful to deny the contribution of one in favour of others. To do so would be to take an unnecessarily limited view and handicap psychiatric research in the process.