This book provides a broad clinical overview of primary and secondary immunodeficiencies nested in clinical cases that will help the reader understand the approach to evaluation, diagnosis, and management of these challenging cases. Chapters begin with a comprehensive overview of immunodeficiencies to ground the reader in practical knowledge of the field and these complex conditions. Chapters cover B lymphocyte immunodeficiency, T cell immunodeficiency, immune dysregulation syndromes, and innate immune defects. They discuss a range of treatment options including gene therapy or bone marrow transplant. The book continues with a discussion on secondary immunodeficiencies and their treatment. Each chapter was written by authors with expertise related to different immunodeficiency disorders and provide a succinct overview of pathomechanisms, diagnosis, and treatment of a specific condition. Primary and Secondary Immunodeficiency will be an excellent resource forpracticing allergists, hematologists, clinical immunologists, fellows, residents, and other clinicians who work with immunodeficiency patients.