The tumor microenvironment is extremely complex and depends on tumor cell interaction with the responding host cells. Angiogenesis, or new blood vessel growth from pre-existing vasculature, is a preeminent feature of successful tumor growth of all solid tumors. While a number of factors produced by both the tumor cells and host responding cells have been discovered that promote tumorassociated angiogenesis, increasing evidence is growing to support the important role of CXC chemokines in this process. As a family of cytokines, the CXC chemokines are pleiotropic in their ability to regulate tumor-associated angiogenesis. In this chapter we will focus on the ELR+ CXC chemokines and their contribution to tumor-associated angiogenesis.