This book presents detailed state of the art knowledge on the humoral primary immunodeficiencies (PIDs), i.e., disorders arising from impaired antibody production due to defects intrinsic to B cells or defective interaction between B and T cells. There is extensive coverage of both basic science discoveries and the latest clinical advances in the field. The book is structured in accordance with the most recent classification of PIDs and also covers updates on the B cell immunological synapse. Readers will find comprehensive, in-depth descriptions of novel humoral PID genes and related clinical applications, mucosal B cells, and the various clinical phenotypes of humoral PIDs. Aspects such as differential diagnosis, clinical management in children and adults, and the role of vaccines are also addressed. The authors are all recognized experts from Europe, Australia, and the United States. Humoral Primary Immunodeficiencies will be of high value for immunologists, pediatricians, rheumatologists, oncologists, internists, and infectious disease specialists and will also be informative for MD and PhD students.