Positive psychology strives to provide a better understanding of well-being and contribute to the promotion of optimal functioning. To this end, the present chapter seeks two objectives. First, after reviewing various well-being conceptualizations, we present a multidimensional definition of Optimal Functioning in Society (OFIS). OFIS refers to high levels of psychological, physical, and relational well-being, with high levels of performance in one’s field of engagement (e.g., work, education, sports) and contributions to society. Thus, this model posits we should consider physical health, along with dimensions of psychological and social functioning, to fully understand well-being. Second, using the Dualistic Model of Passion, we underscore the role of passion for significant intentional activities in the promotion of OFIS. We present research that shows that a more adaptive form of passion (harmonious passion) leads to higher levels of OFIS than a less adaptive passion, namely obsessive passion.