Background and objectives: Older adults are characterized by an attentional preference for positive over negative information. Since this positivity effect is considered to be an emotion regulation strategy, it should be more pronounced when emotion regulation is needed. In contrast to previous studies that focused on the effects of sad mood on attention, we used a stressor to activate emotion regulation and evaluate the effects of different types of mood state changes. Moreover, we evaluated mood effects on attentional processes using a paradigm that allows disentangling between different attentional engagement and disengagement processes. Methods: Sixty older adults were randomly assigned to receive a stressor or a control task. Before and after this manipulation, mood state levels (happy, sad, nervous, calm) were assessed. Next, attentional processing of happy, sad, and angry faces was investigated using an eye-tracking paradigm in which participants had to either engage their attention towards or disengage their attention away from emotional stimuli. Results: Changes in different mood state levels were associated with different attentional disengagement strategies. As expected, older adults who increased in sad mood level showed a larger positivity effect as evidenced by a longer time to disengage attention from happy faces. However, older adults who received the tension induction and who decreased in calm mood level were characterized by longer times to disengage attention from sad faces. Limitations: The stressor was only partially effective as it led to changes in calm mood, but not in nervous mood. Conclusions: These results suggest that older adults may deploy a positivity effect in attention (i.e., longer times to disengage from positive information) in order to regulate sad mood, but that this effect may be hampered during the confrontation with stressors. (C) 2016 Elsevier Ltd. All rights reserved.