In addition to line-sitting, queue-scalping is also widely witnessed in congestion-prone service systems. Unlike true customers, queue-scalpers have no interest in the service being offered and enter the queue with the pure intent to sell their spots. Different from the line-sitting whereby customers pay someone to stand in line on their behalf (Chap. 3), queue-scalping takes a make-to-stock (MTS) approach in that queue-scalpers perpetually circulate in the queue before the arrival of a client, so by the time a buying customer arrives, she can readily take a scalper’s spot and shorten her wait. Thus, its value proposition is waiting-time reduction. In contrast, line-sitting takes a make-to-order (MTO) approach in that a line-sitter joins the queue only after a client requests so, and therefore (unlike queue-scalping), line-sitting does not decrease clients’ wait time but alleviates their waiting costs by diverting them from an on-site queue to an off-site queue. We present a queue scalping model in this chapter. This chapter is based on Yang et al. (Manag Sci 67:6803–6821, 2021) and Wang and Wang (Oper Res Lett 49:485–491, 2021) where interested readers can find proofs of the findings shown in this chapter.