The potential for disproportionately altering outcome in the early stages of rheumatoid arthritis (RA) was first hypothesized in the early 1990s. This window of opportunity hypothesis for therapeutic intervention in RA is based on the existence of a time frame within which there is a potential for a greater response to therapy, resulting in sustained benefits or, perhaps most important, a chance of cure. Given the persistent, progressive, damaging, inflammatory nature of RA, this approach to altering outcome in the early stages seems attractive.