The analysis of queues with multiple servers is typically challenging when the service time distribution is general. Such analysis usually involves an infinite-dimensional process for tracking service ages or residual service times. In “Diffusion Approximation for Efficiency-Driven Queues When Customers Are Patient,” He demonstrates from a macroscopic perspective that, if customers are relatively patient and the system is overloaded, the dynamics of a many-server queue could be as simple as the dynamics of a single-server queue. In particular, the virtual waiting time process can be captured by a one-dimensional diffusion process, which enables us to obtain simple formulas for performance measures, such as service levels and effective abandonment fractions. To justify this diffusion model, a functional central limit theorem is established for the superposition of stationary renewal processes.