Adolescence is a physical, sexual, cognitive, emotional and social development period. Adolescents may experience difficulties about meeting their psychological needs, adapting themselves to changing life conditions. Psychological counseling and guidance services not only focus on identifying and treating psychological disorders, but also they should focus on the positive developmental aspects of mental health. By doing so, they may contribute youths to attain better understanding about their strong aspects and sources they have, to develop effective strategies against life difficulties, to set realistic targets about future, and eventually to obtain psychological well-being (PWB). Adolescents’ positive characteristics may be improved with school-based applications long before problem emerges and before adolescents’ psychological well-being is not ruined, their live skills may be strengthened, and their positive coping skills and selfesteem may be increased. In this chapter we propose to introduce the concept of PWB, to explain variables related to PWB, to discuss the importance of PWB in the field of psychological counseling and guidance.