This thesis has two main objectives. The first objective of this thesis is to examine employees’ experience of HPWS in their respective business units. The second objective is to develop a conceptual model that determines how these perceptions are related to their wellbeing and performance. In doing so, both the mutual gains and conflicting outcomes perspectives have been examined. In addition, POS and JDR theories are proposed as alternative theoretical perspectives in examining the pathways through which HPWS can impact on employee wellbeing and business unit level performance. Specifically, building on the notion of JDR model, job control and supervisor support have been hypothesized as important resources to minimize the negative impact of excessive job demands on wellbeing.