Introduction Despite association between “social capital” and health outcomes having been extensively researched, debate still surrounds which level of analysis is most appropriate to investigate this contextual phenomenon. Traditional contexts such as “neighbourhood” seem only to explain a very small amount (∼ 5%) of total variance in individual health outcomes, often chosen more out of data availability than as representations of individuals' social interactions and networks. The aims of this United Kingdom study are twofold; to investigate the strength of association between social capital and health at individual- and aggregated-levels; and second, to determine which context (household vs neighbourhood) better explains variation in individual-level health.

Methods Applying multilevel analyses to British Household Panel Survey data (N=10 992), we estimated fixed and random effects between individual-, household- and small area-level social capital indicators and general health. We further compared the variance in health attributable to each level using intraclass correlations.

Results Association between social capital and health seems to depend on indicator type and context, with one fifth of individual-level health variance found at the household-level. However, only individual-level variables appear to influence contextual-level variance.

Conclusion Social capital research could be advanced by focusing on contexts based on extended social networks, not just geographic proximity of random individuals. Furthermore, decision makers must now appreciate that social capital interventions targeting health are unlikely to be cost-effective if directed solely at the “community” level, as only small variations in health are attributable to such a context.