Although the role of the home environment in the development of prosocial behaviour in childhood is well-established, the existing research has focused on the emotional microclimate of the home. We do not know whether the physical home environment has a role to play too. The present study aims to fill this gap. It uses data from a large, nationally representative birth cohort survey in the UK, tracking the trajectories of prosocial behaviour in children across ages 3, 5, 7 and 11 years as a function of three constructs derived from the Home Observation Measurement of the Environment Short Form (HOME-SF), assessed at age 3 years: physical organisation of the home, mother's emotional and verbal responsivity, and mother's use of harsh discipline. Prosocial behaviour was assessed via a parent-reported subscale of the Strengths and Difficulties Questionnaire. The findings, which were robust to adjustment for sex, ethnicity, cognitive ability, special educational needs, neighbourhood environment, family income, family structure, maternal mental health, maternal education and religiosity, showed that all three aspects of the home environment were associated with prosocial behaviour. However, when controlling for all three simultaneously, physical organisation ceased to be a significant predictor of prosocial behaviour although the two measures of the home's emotional environment retained their significance. This indicates that, compared to the physical, the emotional climate of the home has a more substantial impact on children's prosocial behaviour. It also suggests that the physical and the emotional context of the home are strongly interrelated, with aspects of emotional harshness possibly mediating the effects of the home's physical disorganisation.