Rheumatoid arthritis is a chronic inflammatory disease characterized by uncontrolled proliferation of synovial tissue and a wide array of multisystem comorbidities. Prevalence is estimated to be 0.8 percent worldwide, with women twice as likely to develop the disease as men. Untreated, 20 to 30 percent of persons with rheumatoid arthritis become permanently work-disabled within two to three years of diagnosis. Genetic and environmental factors play a role in pathogenesis. Although laboratory testing and imaging studies can help confirm the diagnosis and track disease progress, rheumatoid arthritis primarily is a clinical diagnosis and no single laboratory test is diagnostic. Complications of rheumatoid arthritis may begin to develop within months of presentation; therefore, early referral to or consultation with a rheumatologist for initiation of treatment with disease-modifying antirheumatic drugs is recommended. Several promising new disease-modifying drugs recently have become available, including leflunomide, tumor necrosis factor inhibitors, and anakinra. Nonsteroidal anti-inflammatory drugs, corticosteroids, and nonpharmacologic modalities also are useful. Patients who do not respond well to a single disease-modifying drug may be candidates for combination therapy. Rheumatoid arthritis is a lifelong disease, although patients can go into remission. Physicians must be aware of common comorbidities. Progression of rheumatoid arthritis is monitored according to American College of Rheumatology criteria based on changes in specific symptoms and laboratory findings. Predictors of poor outcomes in early stages of rheumatoid arthritis include low functional score early in the disease, lower socioeconomic status, early involvement of many joints, high erythrocyte sedimentation rate or C-reactive protein level at disease onset, positive rheumatoid factor, and early radiologic changes.