Music psychology is the study of how humans experience and perceive music, and the impact this has on individuals, groups and communities. Engaging with music - whether by performing, creating, learning or listening - can have significant benefits across the lifespan. This book explores how music can promote mental health and functioning in diverse settings, from supporting cognitive development in premature babies to establishing identity and emotional well-being in adolescents, to enhancing brain function in adults and challenging cognitive decline in dementia patients. A lifespan approach is used to illustrate that the benefits of musical engagement need not be reserved for the vulnerable, but can also serve people of all ages to enhance health and well-being.