The natural history of rheumatoid arthritis (RA) is best defined by a combination of disease specific measures such as radiographs and remission rates, and patient specific measures such as functional and work disability, total joint replacement, adverse drug reactions, social disruption and premature mortality. Prognosis depends largely on how RA is defined, since clinical RA has a worse and epidemiologic RA a better prognosis. Seronegative polyarthritis confounds the assessment of RA since it has a better prognosis for remission and longterm outcome. RA is a progressive disease in the clinic, particularly in patients with longterm followup. Ongoing cohort studies of recent onset RA may aid in our understanding of RA prognosis, but may still beg the question, what is RA?