We tested a novel multi-component emotion self-regulation construct that captured physiological (vagal tone), cognitive (reappraisal) and temperament (effortful control) aspects of emotion regulation (ER) as a moderator of the link between more stressors and greater negative/less positive affectivity (NA and PA). A socio-economically diverse sample of 151 women with young children completed questionnaires and a laboratory visit (including cognitive and parent-child interaction tasks and vagal tone measurement). Women with more stressors had more NA and less PA. Furthermore, for NA only, having more stressors was substantially associated with NA but only among women with the lowest ER. This pattern was evident for the composite as well as individual indicators of ER. Results were not attributable to individual differences in executive function. Findings are discussed in light of the diathesis-stress model of stress and coping.