Research and theory concerning the nature and sources of well-being has been undertaken through varied approaches. Two such approaches are the capability approach and self-determination theory (SDT), both of which have postulated specific factors deemed necessary for human well-being and flourishing. In two studies we examine the relations between capabilities and well-being indicators, as well as the mediating role of basic psychological need satisfaction in these relations. Results indicate that both capabilities and SDT’s basic psychological needs are substantially associated with well-being, and that SDT’s basic needs partially mediate the relation between capabilities and indicators of wellness.