The thesis consists of four chapters which deal with different determinants and implications of working hours. Chapter 2 investigates the negative effects of long working hours on workrelated stress, how workers manage to reduce this stress by reducing their working hours or switching jobs, and the implications of stress reduction on health outcomes. Chapter 3 investigates the effect of the terrorist attacks that Europe witnessed over the period 2004-2005 on the integration of Muslim immigrants in the Netherlands using subjective as well as objective measures of integration such as working hours. Chapter 4 deals with the part-time pay penalty and investigates to what extent the pay penalty of part-time workers decreased over time due to a convergence in computerization and job tasks between part-time and full-time workers employed within the same occupation. Chapter 5 investigates gradual retirement as a retirement option that provides older workers the opportunity to remain in the labour market while working fewer hours. In this chapter, we study the effect of having the option of gradual retirement on workers’ labour supply. Chapter 6 concludes.