Context: Wellbeing initiatives are commonplace in organisations as more and more leaders see the benefits in implementing initiatives focusing on improving the wellbeing of their people. There is a lot of research examining the direct positive link between wellbeing initiatives on individual job performance, however very few studies have examined the impact of wellbeing initiatives on organisational effectiveness. Purpose: The purpose of this PhD project is to explore how wellbeing is related to organisational effectiveness. This PhD thesis will be broken up into three studies: 1. A case study using qualitative interviews to examine the purpose of employee wellbeing initiatives, the role of wellbeing, and how it is related to organisational effectiveness (Study 1). 2. A scoping review synthesising existing literature examining the psychosocial safety maturity models (Study 2). 3. Developing and testing (using the Delphi method) a Psychosocial Safety maturity model, encompassing both a risk management approach and a health promotion approach (Study 3).