The proportion of UK employees who are part-time, temporary, agency staff, on zero hours contracts or self-employed has increased since PH22 was published in 2009. The Stevenson/Farmer review ‘Thriving at work’ estimates that 15% of UK workers have an existing mental health condition. Better mental wellbeing and job satisfaction are associated with increased workplace performance and productivity (Department for Business Innovation & Skills 2014). However, many employers know the value of positive mental wellbeing but do not know how to promote it. Therefore, the objective of this review is to: identify what universal organisational-level approaches, programmes, strategies or policies are effective and cost-effective at: ○. Preventing poor mental wellbeing. ○. Promoting positive mental wellbeing. ○. Improving mental wellbeing. Identify what interventions or strategies are effective and cost-effective at; ○. Recognising and engaging employees who may require support for their mental wellbeing. ○. Identifying periods of high risk within an organisation. Understand the views and experiences of those employees, employers and those delivering the intervention. The relationship between organisational approaches and mental wellbeing outcomes for employees is complex and can be influenced by a range of factors including work stressors and work-related resources.