Support is often proposed as a way in which supervisors can help employees cope with the negative impact of role stressors and other workplace demands (also referred to as the stress-buffering effect). However, there are numerous findings of reverse-buffering effects of support in the stressor–strain relationship. In the present research, the extent to which supervisors’ ability to regulate their own negative emotions determines if the support they provide has a positive (buffering) or negative (reverse-buffering) effect on the relationship between role overload and employee outcomes was investigated. Three-way interactive relationships among role overload, supervisor support, and supervisor emotion management were tested in 2 samples of Australian employees in the prediction of burnout and turnover intentions. Sample 1 consisted of 139 employees from the waste services industry. Sample 2 employees were from an organization in the education and training industry (N = 125). Across both samples, the hypothesized stress-buffering effect of support from supervisors high in emotion management was supported. Results also showed that support from supervisors low in emotion management exacerbated role overload. These findings help to explain contradictory findings in the literature on the role of supervisor support in shaping employees’ responses to demands encountered in the workplace.