Common variable immune deficiency (CVID) is the commonest symptomatic primary immunodeficiency and represents a heterogenous collection of disorders resulting mostly in antibody deficiency and recurrent infections. However, autoimmunity, granulomatous inflammation and malignancy frequently occur as part of the syndrome. The etiology of the condition has been poorly understood although in recent years, significant progress has been made in elucidating genetic mechanisms that can result in a CVID phenotype. In parallel to this, advances in treatment of the condition have also resulted in improved survival and quality of life for patients. There still remains significant work to be done in improving our understanding of the disease. In addition, recognition of the condition remains poor with significant diagnostic delays and avoidable morbidity. In this article, we review CVID with a particular focus on the areas of improving diagnosis and classification, recent developments in understanding the underlying etiology and genetics; and current treatment and monitoring recommendations for patients.