Perfectionism has been associated with higher levels of psychological maladjustment and disorder in adolescence and lower levels of subjective well-being and psychological adjustment. Perfectionism, however, is a multidimensional disposition, and not all dimensions of perfectionism are necessarily unhealthy and maladaptive. This entry presents an overview about perfectionism in adolescence and the main dimensions of perfectionism: perfectionistic strivings and perfectionistic concerns. It shows how the two dimensions are related to subjective well-being, psychological adjustment and maladjustment, and disorder. Moreover, it informs on how perfectionism can be measured and what factors influence the development of perfectionism in children and adolescents. Moreover, it will discuss what is still unknown about perfectionism and why the notion that perfectionism can be healthy or adaptive is controversially debated.