Wellness promotion addresses both the reduction of disorder and disease and the enhancement of mental and physical health. There is increasing evidence of a strong and reciprocal relationship between mental and physical health, and linking these two areas may be particularly useful for promoting positive youth development in school contexts. This article discusses the relationship between mental and physical health in children and adolescents, and how to promote both within schools. Topics discussed include the benefits of (a) hope and optimism, (b) structured extracurricular activities, and (c) sport and exercise psychology for school-based health and wellness promotion. These topics are linked in that each has the potential to positively affect both mental and physical health in children and adolescents in schools.