With the increased emphasis on measuring school success primarily through academic outcomes, some might argue that school professionals cannot afford to pay much attention to students' well-being, especially to such a frivolous component as happiness. Indeed, even some positive psychologists who encourage greater attention to research and promotion of "optimal functioning" in adults and children are careful to discourage psychologists and other professionals from equating positive psychology with "happyiology" as though the promotion of happiness is less important than the promotion of other positive psychology constructs (e.g., meaning in life, virtuous behavior, etc.). Although the author agrees with the notion that the promotion of happiness is a limited goal and does not represent the full array of indicators needed to reflect optimal well-being, he also believes that convincing evidence has been uncovered during the past several decades that demonstrates the importance of students' happiness to their success in school and other important arenas in life. Actually, he believes that students' current happiness levels are important in their own right. Nevertheless, it is recognized that school professionals may demand a stronger rationale to devote attention to such matters, given the mandated central importance of academic outcomes. Thus, this article is devoted to reviewing the literature on the importance and promotion of the happiness of children and adolescents.