The four-day school week is a school calendar that has become increasingly common following the COVID-19 pandemic. Proponents of the calendar often claim that offering teachers a regular 3-day weekend will help schools better retain existing teachers and recruit new teachers to their district without incurring additional costs due to higher salaries or other pecuniary benefits. However, there is scant empirical evidence assessing these claims. I use difference-in-differences and synthetic difference-in-differences models to assess the impact of four-day school week calendars on teacher retention and teacher quality in Arkansas. I find evidence that the calendar may help retain teachers who otherwise would have moved to another school and suggestive evidence that retention in non-adopting schools may be harmed by the four-day school week adoption in nearby districts. Results examining changes in teacher quality are inconclusive. These results have significant implications given the rapid growth in four-day school week calendars in recent years.