Despite the therapeutic improvements with recent biologic agents approved for rheumatoid arthritis (RA), there is still a significant unmet medical need for the treatment of subjects with this chronic disease to achieve a faster, more complete response, and higher rates of remission. This study is an open-label extension study for subjects who have participated in one of the qualifying development program studies with mavrilimumab. Participation in this study will allow these subjects to continue to receive long-term treatment with mavrilimumab. The data from this study will provide an evaluation of the long-term safety of mavrilimumab in adult subjects with RA. In addition, long-term exploratory efficacy outcomes such as joint damage and disability will be evaluated.