It has long been assumed that the immune system plays a role in tumor eradication, however, scant clinical evidence exists to support that hypothesis. In recent years, as the immune system and its specific effector cells are better defined, convincing data supporting immune surveillance is emerging. Several studies have shown that an "immune signature" in the tumor microenvironment is associated with a superior outcome in a variety of cancer types. Moreover, studies have suggested that T cells found in high density within the tumor parenchyma are also correlated with a survival benefit. The type of adaptive immune response implicated in improved cancer outcomes is a type 1 response. That is, adaptive immunity associated with T cells that secrete pro-inflammatory cytokines, such as IFN-gamma, which can not only support a proliferative antigen specific T cell response but also enhance "cross priming" by activating antigen presenting cells local to the tumor site. There are many methods available that will allow the development of clinical reagents designed to stimulate Th1 immunity; either by in vitro or in vivo manipulation. Clinical trials of a variety of immunotherapeutic strategies indicate that the generation of tumor antigen specific Th1 may be beneficial in inhibiting the growth of common solid tumors.