The ability to modulate the body's immune system can greatly assist the treatment of diseases and repair of injured tissues. Immunomodulatory biomaterials can promote adaptive immunity, without the need for drugs, cytokines or cell therapies. Their design can be targeted towards specific applications, including cancer and inflammatory disease. Exploring the latest research, the authors present their philosophy for the design of immunomodulatory biomaterials and aim to close the gap between materials scientists, engineers, and biologists. The book includes an overview of the immune system, the immune response biomaterials may create, and various design strategies across a range of biomedical contexts. The book concludes with an outlook on the future of this topic and how it will translate to the clinic.