The Society for Immunotherapy of Cancer (SITC) has expanded efforts to respond to the exponential growth of educational needs by offering primers at the Annual Meeting, itinerant courses to health care providers domestically and internationally, topical meetings and task forces addressing salient questions related to the field, specifying guidelines for patient toxicity management, policy and quality benchmark development, and informing on other themes as they emerge through the SITC portal. In this context, SITC leadership decided to update, refine, and broaden the legacy established by the first edition of this textbook by providing a second edition that targets primarily young basic and clinical investigators but is informative to as many other constituencies as possible. The new edition of Cancer Immunotherapy Principles and Practice updates chapters of the first edition while introducing new ones to cover emerging concepts. Chapters for textbooks can be painstakingly overbearing, but all contributors managed to complete their part to bring together cutting-edge insights that every translational investigator and practicing clinician needs to know about tumor immunology and immunotherapy. The textbook is divided into five sections: Basic Principles of Tumor Immunology, Cancer Immunotherapy Targets and Classes, Immune Function in Cancer Patients, Disease-Specific Treatments and Outcomes, and Regulatory Aspects of Cancer Immunotherapy. These sections cover the continuum from basic principles to practical and clinically relevant information to allow critical understanding of the development and testing of novel therapeutics, companion diagnostics, and useful biomarkers, and inform about the regulatory processes that support the safe and efficient delivery of immunotherapy to patients with cancer. In addition, the chapter on the history of immunotherapy was not only preserved but updated to honor and recognize those who pioneered and championed the field.