This study will test whether the drug combination of methotrexate and infliximab (anti-TNF-alpha antibody) is more effective than methotrexate alone for treating rheumatoid arthritis early in the disease. (The Food and Drug Administration has approved both treatment regimens for patients with long-standing rheumatoid arthritis.) The study will also evaluate how effectively magnetic resonance imaging (MRI) can detect differences in the development of bone damage in the two treatment groups by as early as 6 months.||Patients 18 years of age and older who have had rheumatoid arthritis for less than 2 years and who have four or more affected joints may be eligible for this 1-year study. Patients must have received methotrexate treatment in the past without complete success, and must not have been treated previously with Anti-Thymocyte therapy.||All participants will receive 20 Mg./week of methotrexate. In addition, patients will be randomly assigned to receive a monthly infusion of infliximab or placebo (a fluid that contains no active drug). After 6 months, all patients will receive active infliximab for the remaining half year of the study. Patients will also receive folic acid (1mg/day), Vitamin D (400 IU/day), and calcium supplements. They may continue to take prednisone (no more than 10 Mg./day) and non-steroidal anti-inflammatory drugs (NSAIDS). Medication dosages will be adjusted as needed if pain and joint swelling worsen. Over the course of the study, patients will come to NIH for 15 visits and undergo the following tests and procedures:||Joint examination-at every visit.|Drug side effects evaluation-at every visit during the study and after the study at 24 and 36 months by questionnaires to be filled out and returned.|Hand and feet X-rays at the first visit, at 6 months and at 12 months.|MRIs of the wrist to examine damage in the bone and synovial tissue (tissue lining the joint)-before treatment begins and at weeks 15, 27 and 54. For this study, the patient lies still in a narrow cylinder (the scanner) with a strong magnetic field. A contrast material (gadolinium) is injected into the blood to enhance the images of the synovium. The MRI takes about 45 minutes.|DEXA scans (dual emission X-ray absorptiometry) of the lower spine, one hip and one wrist to measure bone density and assess bone loss-before treatment begins and at weeks 27 and 54. This X-ray test takes about 5 to 10 minutes.|CTs (computed tomography) of one hand to assess joint damage in the wrist-before treatment begins and at weeks 27 and 54. Only half the patients in the study will have this X-ray study, which produces 3-dimensional images of the hand. It will be done to compare the location, size and change of damage in the wrist seen on CT with the information obtained on MRI. The procedure takes about 5 to 10 minutes to complete.|Blood tests-at every visit to evaluate treatment response and side effects.