This research aims to identify how we can work with early-years services to give disadvantaged children a better start in life. Children from socially disadvantaged backgrounds often have poorer health and developmental outcomes by age 5. Services in the early years try to support these families, but they don’t always work well for everyone. The research will analyse the data in the Born in Bradford’s Better Start (BiBBS) interventional birth cohort to find out which families go to what early-years services, and for whom these services work. It will also speak to families to learn what works best for them. The findings will then be used to co-produce solutions and adaptations to existing services to make them more accessible and better able to improve child outcomes.