Due to an ageing society, an increasing retirement age, and high prevalence of chronic health problems among older persons, it is important to understand how older employees [with health problems] can work for longer and productively, often this is termed ‘sustainable employability’. This context brought about the research presented in this thesis, financed by the Department of Public Health of the Erasmus MC and the Netherlands Organisation for Applied Scientific Research TNO. The longitudinal questionnaire study ‘STREAM’ (Study on Transitions in Employment, Ability and Motivation) was the basis for the research (www.tno.nl/stream). STREAM was financed by the Dutch Ministry of Social Affairs and Employment. Due to an ageing society, an increasing retirement age, and high prevalence of chronic health problems among older persons, it is important to understand how older employees [with health problems] can work for longer and productively, often this is termed ‘sustainable employability’. This context brought about the research presented in this thesis, financed by the Department of Public Health of the Erasmus MC and the Netherlands Organisation for Applied Scientific Research TNO. The longitudinal questionnaire study ‘STREAM’ (Study on Transitions in Employment, Ability and Motivation) was the basis for the research (www.tno.nl/stream). STREAM was financed by the Dutch Ministry of Social Affairs and Employment. The main conclusions of the thesis are as follows: Highly engaged workers have greater improvement in physical and especially mental health during one-year follow-up than less engaged workers. Employees with an active, non-avoidant, coping style have a better work ability than employees with a non-active and avoidant coping style. Poor health adversely affects sustainable employability, this is especially the case for psychological health problems. However, favourable psychosocial work-related factors play an essential role, such as high autonomy and social support. These factors have a positive influence on sustainable employability, especially for workers with health problems. In conclusion, especially the promotion of favourable psychosocial work-related factors has the potential to greatly reduce that adverse health effects on sustainable employability.