Perceived organizational support (POS) is defined as employees’ beliefs concerning the extent to which their organization values their contributions and cares about their well-being. A considerable body of evidence indicates that the more employees experience a high POS, the more they are likely to develop commitment toward their organization. Particularly, POS is the strongest driver of affective organizational commitment. The objective of this chapter is fourfold. First, the authors review the literature linking POS to the three dimensions of organizational commitment delineated by Meyer and Allen (1991) and detail the mechanisms underlying these relationships. Second, they extend their review to other sources of perceived support and other foci of commitment. Third, they consider new suggestions for future research on support and commitment. Finally, they conclude with a discussion of practical implications of support_commitment relationships. Reference: Meyer, J.P. and Allen, N.J. (1991). A three-component conceptualization of organizational commitment. Human Resource Management Review, 1, 61_89.