Leverage of the body’s own immune system is revolutionizing the way that we treat cancer as it can lead to dramatic and durable responses. Such anti-tumor therapies include reactivation of anti-tumor T cells, expansion of tumor-infiltrating lymphocytes (TILs), Chimeric antigen receptor (CAR) T cells and a variety of cancer vaccines. The focus or target of most these approaches are cells of the lymphocytic lineage (T, B, NK, dendritic cells), key components of both adaptive and innate immune response. At the same time, lymphocytes can also be malignant, as in the case of a large number of lymphocytic leukemia and lymphoma subtypes, and active components of the immune microenvironment, controlling tumor growth and anti-tumor response. This conference for the first time brings together scientists from these different areas of lymphocyte biology and provides an overview of lymphocyte development, transformation, terminal differentiation, location within the tumor microenvironment and anti-tumor activity. The conference also provides an update on novel therapy protocols that attempt to harness the function of lymphocytes against cancer and state-of-the-art technologies, including imaging and DNA/RNA sequencing approaches, that will help us visualize and molecularly dissect anti-tumor responses in experimental systems and cancer patients.