Occupational stress research has traditionally had an individual-level focus, concentrating on how individual employees perceive their work environment and react to it (Bliese & Jex, 1999). However, it is recognised that understanding of the occupational stress process would be enhanced by the use of multilevel analyses, where the influence of both individual- and group-level perceptions of the work environment can be directly modelled and understood (Bliese & Jex, 1999). The objective of this thesis was to test a multilevel model of occupational stress to more fully understand the impact of the workgroup psychosocial environment on employee well-being, and subsequent organisational outcomes. Three studies were designed for this purpose, variously using cross-sectional, longitudinal, and quasi-experimental designs. A review of the existing multilevel occupational health psychology literature was also conducted.