Notes: Aims.  This paper reports a study which aims (1) to investigate and compare levels of stressors and burnout of qualified and unqualified nursing staff in acute mental health settings; (2) to examine the relationships between stressors and burnout and (3) to assess the impact of social support on burnout and stressor–burnout relationships.Background.  Several studies have noted that the work of mental health nurses can be highly stressful, but relatively few have focused specifically on staff working in acute inpatient settings. Although many of the pressures faced by this group are similar to those in other nursing specialities, a number of demands relate specifically to mental health settings, including the often intense nature of nurse–patient interaction and dealing with difficult and challenging patient behaviours on a regular basis.Methods.  A convenience sample of 93 nursing staff from 11 acute adult mental health wards completed the Mental Health Professionals Stress Scale, Maslach Burnout Inventory and House and Wells Social Support Scale.Results.  Lack of adequate staffing was the main stressor reported by qualified staff, while dealing with physically threatening, difficult or demanding patients was the most stressful aspect for unqualified staff. Qualified nurses reported significantly higher workload stress than unqualified staff. Approximately half of all nursing staff showed signs of high burnout in terms of emotional exhaustion. A variety of stressors were positively correlated with emotional exhaustion and depersonalization. Higher levels of support from co-workers were related to lower levels of emotional exhaustion. Higher stressor scores were associated with higher levels of depersonalization for staff reporting high levels of social support, but not for those reporting low levels of support (a reverse buffering effect).Conclusions.  Qualified and unqualified nursing staff differed in terms of the prominence given to individual stressors in their work environment. The findings were consistent with the notion of burnout developing in response to job-related stressors. While staff support groups may be useful in alleviating feelings of burnout, the reverse buffering effect suggests that they should be structured in a way that minimizes negative communication and encourages staff to discuss their concerns in a constructive way.