OBJECTIVE: To investigate the physical, social and psychological environment of families with preschool-age children to identify the most significant risk factors for unintentional injury. DESIGN: A 1-year prospective case-control study, using a health-visitor-administered questionnaire. SETTING: East and Midlothian, Scotland. SUBJECTS: Seventy-nine children under 5 years of age presenting to an accident and emergency (A&E) department during 1998-1999 with an unintentional home injury and 128 matched controls. RESULTS: Of 264 families, 207 responded (78.4% response rate). The main carers of cases had a lower level of educational attainment than controls (P<0.01). This factor explained the case carer leaving fulltime education earlier, being less likely to be married and more often in receipt of government benefits. Cases lived in households with larger numbers of children, were more likely to have a physical illness, were less likely to have had a non-medically attended injury in the previous year (P<0.01) but more likely to have had another A&E injury attendance. Case households had lower electrical socket cover utilization (P<0.01) and fewer thought their child had adequate access to safe play areas. The main carers of cases tended to have a more negative life event experience in the preceding 6 months, but showed no significant differences in physical or mental well-being or social support. Cases seemed to be slightly more deprived members of their community. CONCLUSIONS: The main carer's educational attainment and socket cover utilization were lower in case families. These risk factors could be used to target families for injury-prevention work. Initiatives to raise educational achievement in the general population could lead to reductions in childhood injuries.