Brain health is the state of brain functioning across cognitive, sensory, social-emotional, behavioural, and motor domains, allowing a person to realize their full potential over their life course, irrespective of the presence or absence of disorders. From as early as pre-conception, numerous factors can affect our brain health. Brain health can be optimized by addressing five determinant clusters across the life course, including physical health, healthy environments, safety and security, lifelong learning and social connection, and access to quality services. Addressing the risk and protective factors that impact the brain through both individual and population-level interventions, including supportive policies and legislation, is essential for promoting lifelong brain health. Beyond individual health and well-being benefits, prioritizing brain health can also positively impact a country’s economy. This chapter outlines key brain health determinants and how to optimize brain health throughout life. To help promote brain health across the life course globally, the World Health Organization has developed a range of technical tools and products, a selection of which will be briefly outlined in this chapter.