A special issue of the *American Journal of Public Health* (Oct 2013) includes an article by [Arline Geronimus](http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2013.301380) on the impact of socially structured stress in young and middle adulthood on later life health, and one by [Colter Mitchell](http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2013.301382) et al. on the implications for health research of differential genetic sensitivity to socio-environmental factors.