This protocol will examine blood, synovial fluid and synovial tissue from patients with rheumatoid arthritis and other chronic inflammatory joint diseases to study genetic and immunologic factors involved in the cause, development and progression of these conditions. Synovial fluid is the lubricating fluid in joints. The synovial membrane is a delicate tissue lining the inner surface of joints, which, in arthritic conditions, thickens and becomes infiltrated with various types of cells.