This study used data from the British National Child Development Study (NCDS) to examine the relationship between materialism/postmaterialism and later mental health. Materialism/postmaterialism was assessed (using Inglehart's 4-item index) at age 33 and mental health (measured by the GHQ-12) was assessed at age 42. It was found that after controlling for socio-economic status at birth, father and mother involvement in early childhood, parental family structure throughout childhood, psychological maladjustment in adolescence, educational attainment and contemporaneous factors (labour force participation, self-reported physical health, belonging to a religion, and being partnered) materialism was negatively related to ill mental health in men. The relationship between materialism and later mental health became insignificant, however, once self-efficacy was entered in the model, suggesting that materialism was positively associated with self-efficacy which was positively related to mental health. Postmaterialism was insignificantly related to mental health in both men and women.