Lifecourse approaches to healthy ageing recognise that health in older age is affected by long-term cumulative inequalities between socio-economic status (SES), gender and ethnicity groups, which begin in childhood. Combining longitudinal survey data with lifecourse history interviews from 729 older New Zealanders aged 61–81 (mean = 72, standard deviation = 4.5), we tested a lifecourse model of predictors of physical, mental and social health in older age. Latent growth curve and mediation analysis showed that the link between childhood SES and late-life health (over 10 years) was mediated by education, occupation and adult wealth. To account for the moderating effects of gender and ethnicity, we modelled the effects for sub-groups separately (225 non-Māori women, 158 Māori women, 219 non-Māori men and 127 Māori men). Childhood SES was an important predictor of later-life health, mediated by education and adult SES for all participants and for non-Māori men. However, there were significantly different pathways for Māori men and for women. Māori men and women and non-Māori women did not attain the same health benefits from higher childhood SES and education as non-Māori men. Findings point to the importance of considering the mediators of lifelong impacts on health in older age, and recognition of how membership of different socially structured groups produces different pathways to late-life health.