In this chapter, we introduce the current techniques and the remaining challenges for establishing inter-AS LSPs with QoS guarantees. We describe the workings of the inter-domain routing system. We discuss the consequences of path selection made by the current inter-domain routing system on the visibility of the paths. The limited visibility of path diversity does not actually prevent the establishment of inter-AS LSPs with QoS guarantees. Rather, the lack of QoS information requires clever heuristics to be designed in order to guide the search towards feasible QoS paths. We cover the existing signaling extensions to RSVP-TE that support the establishment of inter-AS LSPs, as well as the protection of those LSPs. The path computation techniques that have been proposed at the IETF are also detailed. Such computation techniques make it possible to ﬁnd the LSP segments within each AS, in order to compose an end-to-end LSP with QoS guarantees when the sequence of ASs to be crossed is known. Finally, combine these three components, i.e. inter-domain routing, LSP signaling and path computation techniques. We show that inter-AS QoS is not beyond reach, but that more work needs to be done in speciﬁc areas, especially concerning heuristics to guide the search towards AS sequences across which feasible QoS paths can be found.