This chapter discusses the implementation of quality of service (QoS) in a Multiprotocol Label Switching Protocol (MPLS) backbone. You will find several design options with different levels of granularity and complexity. Most designs use Differentiated Services(DiffServ) as a base technology and equally apply to pure IP backbones. Some designs in-corporate MPLS Traffic Engineering (MPLS TE) to improve the performance characteristics of the network and are specific to MPLS backbones. Many factors influence the selection of the most appropriate design for a particular network. Although the services the network provides are of prime importance, bandwidth and operational costs can play an important role in the design selection. Overall, the backbone uses a simpler QoS model when you compare it with the designs that network services require. This chapter focuses exclusively on the implementation of QoS in the backbone to support multiple services. In most cases, those services have their own QoS implementations that you need to integrate with your backbone design.