In this paper we aim to provide an overview of initial findings from the UK AESOP study concerning ethnicity, social risk factors and psychosis, and to set the findings from this study within the context of other related research. Our focus is primarily on the UK African-Caribbean population. AESOP is a multi-centre population based incidence and case-control study of first episode psychosis, conducted initially over a three-year period. The study sample comprises: a) all patients with a first episode of psychosis who presented to secondary and tertiary services within tightly defined catchment areas in south-east London, Nottingham and Bristol, UK over defined time periods; and b) a random sample of healthy community controls. Findings from the AESOP study to date have confirmed that the African-Caribbean and Black African populations in the UK are at increased risk of schizophrenia and other psychoses, compared with the White British population. Analyses of data relating to social risk factors suggest that various forms of early childhood and adult adversity, and neighbourhood characteristics, including ethnic density, may be particularly important in contributing to increased risk in these populations. These data suggest that adverse social experiences may be aetiologically relevant in schizophrenia and other psychoses. A more complete understanding of these factors may help us to clarify why there are differences in rates between populations.