Although cognitive function may decline to some extent with increasing age, evidence suggests that it retains a degree of plasticity and can continue to be shaped even in later life. A life-course approach has been adopted for both the detection of dementia risk and the development of prevention strategies throughout the lifespan. This chapter introduces the theoretical foundations of the life-course approach to cognitive health, analyses risk factors for cognitive decline from a life-course perspective, and offers recommendations for developing prevention and intervention strategies to address cognitive decline across the life-course.