This paper analyzes whether part-time employment is beneficial for firm productivity in the service sector. Using a unique dataset on the Dutch pharmacy sector that includes the work hours of all employees and a “hard” physical measure of firm productivity, we estimate a production function including heterogeneous employment shares based on work hours. We find that a larger part-time employment share leads to greater firm productivity. Additional data on the timing of labor demand show that part-time employment enables firms to allocate labor more efficiently. First, firms with part-time workers can bridge the gap between opening hours and a full-time work week. Second, we find that during opening hours part-time workers are scheduled differently than full-timers. For example, we find that part-time workers enable their full-time colleagues to take lunch breaks so that the firm can remain open during these times.