Heilmann and colleagues examine neighbourhood belonging and social cohesion as modifiable social conditions with consequences for family mental wellbeing. Using baseline data from an ethnically diverse community sample in England, the study distinguishes parental wellbeing from children’s socio-emotional outcomes and tests whether associations differ by demographic and socioeconomic characteristics. The principal finding is asymmetric: stronger neighbourhood belonging and cohesion are associated with better parental mental wellbeing, while associations with children’s difficulties are more contingent after adjustment. This prevents neighbourhood cohesion from being treated as a universal psychological remedy. The theoretical contribution lies in understanding neighbourhood effects as socially distributed and population-specific. Methodologically, the paper combines validated scales with multivariable regression in a sample deliberately attentive to ethnic diversity, addressing a weakness in earlier UK evidence. It bridges public health, community psychology and neighbourhood research by showing how local social relations can operate as health-relevant infrastructure while remaining irreducible to physical design alone.