This book is intended to serve as an authoritative reference source for a broad audience involved in the research, teaching, learning, and practice of nanotechnology in immunotherapy. The combination of nanotechnology and immunotherapy is recognized as a promising treatment modality. In particular, the use of nanoparticles in immunotherapy has attracted increased attention for their unique efficacy and specificity in cancer treatment. A wide variety of nanoparticles, such as polymeric and liposomal nanosystems, carbon nanotubes, and gold nanoparticles have provided important nanoplatforms for immunotherapeutic approaches. They have been shown to improve delivery and efficacy of immunotherapeutic agents such as vaccines or adjuvants. Nanoparticle-mediated thermal therapy has demonstrated the effectiveness for precise tumor cell ablation, radio-sensitization of hypoxic regions, enhancement of drug delivery, activation of thermosensitive agents, and enhancement of the immunesystem. Plasmonic nanoparticles are a special type of metallic nanoparticles that has received great interest due to their enhanced optical and electromagnetic properties and their superior capacity to convert photon energy into heat for selective photothermal therapy at the nanoscale level. Nanoparticle sizes can also be controlled such that they accumulate preferentially in tumors due to the enhanced permeability and retention effect of tumor vasculature. Various nanosystems such as gold nanoparticles have also been shown to stimulate the immune system. Immunotherapies could thus synergistically benefit from the combination with targeted nanoparticle-mediated photothermal therapies, especially when hyperthermia around immune-checkpoint inhibitors in the tumor bed is combined with precise thermal ablation of cancer cells. Of great importance is the possibility that such an approach can induce long-term immunological memory that can provide protection against tumor recurrencelong after treatment of the initial tumors, like an anticancer vaccine. Nanoparticle-mediated immunotherapy could lead to an entirely new treatment paradigm that challenges traditional surgical resection approaches for many cancers and metastases.