Using longitudinal data (N=220), we examined the contribution of perceived organizational support and four mindsets of organizational commitment (affective, normative, perceived sacrifice associated with leaving and perceived lack of alternatives) to employee psychological well-being. In order to assess the contribution of support and commitment independently from workplace stressors, we controlled for the effects of role ambiguity, role conflict and role overload. Analyses showed affective organizational commitment to mediate a positive relationship between perceived organizational support and well-being. In addition, perceived organizational support negatively related to perceived lack of employment alternatives which, in turn, was negatively related to well-being. Normative commitment and perceived sacrifice associated with leaving were unrelated to well-being. The implications of these findings are discussed under the lenses of social exchange and conservation of resources theories. (Contains 3 tables and 2 figures.)