The American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) have defined remission using Boolean- or index-based criteria (i.e., a Simplified Disease Activity Index [SDAI] score of ≤3.3). We undertook this study to compare definitions of remission to inform choice of end points for future rheumatoid arthritis (RA) clinical trials, and we also included in our comparison the remission criterion of a score of ≤2.8 on the Clinical Disease Activity Index (CDAI).