Previous research has shown that work-related stress is associated with various types of negative health outcomes. With work being a large part of individuals’ lives, looking at the effects of straining work over a lifetime of work is therefore relevant in order to understand how the work environment affects health. This study will investigate the work environment by the demands and control individuals have at their workplace. Life course theory combined with the theory of cumulative advantage/disadvantage will help to create a framework for studying long-term and cumulative effects of the work environment on psychological well-being. Thus, the aim of the study is a) to understand how job strain affects psychological well-being and b) to provide knowledge on long-term effects of job strain on psychological well-being. The findings are based on panel data from the Swedish Level-of-Living Survey from the years 1981-2010, with 9-10 years between the measurement periods. High strain jobs (high demands and low control) are shown to have the most damaging effects on psychological well-being, whereas low strain jobs (low demands and high control) are shown to be the least damaging work environment. No significant long-term effects are found.