Immunotherapy has revolutionized the treatment of cancer. Most modalities of cancer immunotherapy work by enabling cytotoxic CD8 T cells to recognize and kill cancer cells. These cells, however, do not work in isolation and are inextricably shaped by the aberrant tumor microenvironment (TME), which includes other immune cells such as macrophages and dendritic cells, as well as acellular components such as the extracellular matrix (ECM). We seek to understand the intrinsic and microenvironmental regulation of cytotoxic CD8 T cell function in the context of tumors. We take advantage of novel genetically engineered mouse models to mark specific states of T cells and macrophages, high dimensional immune profiling, live imaging, in vitro 3D ECM culture systems and a variety of other techniques.