This research protocol will evaluate subjects with systemic lupus erythematosus (SLE) and their relatives to study the pathogenesis and natural history of the disease and the mechanisms leading to enhanced organ damage. Patients will be evaluated by a history and physical examination and routine laboratory studies will be obtained as needed to assess disease activity or complications of the disease and to monitor for drug-related toxicities. Blood, skin or urine specimens may be requested for research purposes, including genetic studies. In addition, a subset of these patients will undergo several tests to understand the pathogenic changes affecting their blood vessels. Patients who are eligible for other research protocols will be offered the opportunity to participate in these studies by signed informed consent. Any medical care recommended or provided to the patient will be consistent with routine standards of practice and provided in consultation with the patient s referring physician. Blood and urine samples and cardiovascular testing will also be collected or performed on healthy volunteers for research purposes and to support the identification and validation of new biomarker candidates.