This chapter describes the principles of the lifecourse perspective and its potential for examining the origins of health and disease (DOHaD). DOHaD research, framed by a lifecourse perspective, accounts for how experiences ’get under the skin’ by influencing biological functions during developmental windows of opportunity, transforming lifecourse trajectories, and affecting intergenerational health patterns. We go on to investigate how exposures and experiences influence different individuals in different ways, with some more vulnerable or susceptible to risk than others, resulting in significant variability in developmental outcomes. Yet, even when taking differential susceptibility into account, there are cross-cutting themes in research focusing on a wide range of disease outcomes in adulthood. These include socio-economic disadvantage and early adverse experiences, which result in a generalised susceptibility to risk. We conclude with a discussion on the limitations of current work in this field, and future directions and priorities for research, including more integrated, multidisciplinary approaches and longitudinal research designs, as well as more sophisticated statistical methods of analysis that move beyond correlational methods and simple causal models.