I am a New Zealand advanced trainee in paediatrics seeking to become an academic clinician. I developed the proposed doctoral project while working with vulnerable New Zealand children experiencing poor health and developmental outcomes. Early life environments and experiences have enduring effects upon later life outcomes. However, significant health and developmental disparities are evident by school-entry. I seek to identify pathways to better health, particularly for vulnerable children. Using data from a contemporary New Zealand birth cohort, life course epidemiological methods, and adopting a holistic view of health, I will describe how health disparities emerge over the preschool years. After analysing cross-sectional outcomes and constructing individual developmental trajectories, the effects of multiple socio-environmental factors upon these trajectories will be statistically modelled to identify key patterns of risk and resilience. The outputs will contribute new knowledge of specific New Zealand relevance and identify priority areas for intervention and policy development.