Over the past five years, the private sector, policymakers, and civil society have developed a growing interest in reduced working hours. The rapid growth of 4-day workweek4-day workweek pilots4-day workweek pilots in multiple firms across different countries has led to considerable scholarly attention regarding this topic. However, most of this discussion is taking place outside of the academic domain. The lack of representativeness of academic literature on the ongoing debate implies that a comprehensive scientific review of theArguments arguments4-day workweek arguments about the 4-day workweek4-day workweek is still missing. This chapter fills this gap by critically assessing the most frequently cited argumentsArguments for adoptingAdopting shorter weeks—increasing productivity, improving well-being, correcting gender imbalancesGender imbalances, and reducing environmental impact—showing that some of theseArguments arguments4-day workweek arguments lack sound scientific support. It frames the 4-day workweek4-day workweek discussion in the general debate aboutReducing working time reducing working timeWorking time in different periods in timeDifferent periods in time and discusses the results of the main 4-day workweek4-day workweek pilots4-day workweek pilots carried out over the most recent years.