Sickle cell disease (SCD) is the most common genetic disorder of the blood. The disease produces significantly abnormal hemoglobin (Hgb) molecules in red blood cells (RBCs). The sickling of RBCs occurs when partially or totally deoxygenated Hgb molecules distort their normal disk shape, producing stiff, sticky, sickle-shaped cells that obstruct small blood vessels and produce vasoocclusion as well as the disruption of oxygen to body tissues. Because tissue damage can occur at multiple foci, patients with SCD are at risk for other medical complications including, but not limited to, delayed growth and sexual maturation; acute and chronic pulmonary dysfunction; stroke; aseptic necrosis of the hip, shoulders, or both; sickle cell retinopathy; dermal ulcers; and severe chronic pain. The chronicity of the illness combined with frequent hospitalizations for pain and other medical management can contribute significantly to impaired psychosocial functioning, altered intra- and interpersonal relationships, and reduced quality of life. Unlike previous qualitative reviews of SCD, this article describes the relevant clinical and research data on the relation between psychosocial functioning and SCD in adult and child populations. The authors discuss the significant role of psychosocial issues in the trajectory and management of the disease and conclude that understanding the pathophysiology of SCD without thoroughly understanding the equally important psychosocial influences is misunderstanding SCD.