The main purpose of this study is to evaluate the effects of LY3541860 in adult participants with moderately to severely active Rheumatoid Arthritis with inadequate response to a least one biologic disease-modifying antirheumatic drug (bDMARD)or targeted synthetic disease-modifying antirheumatic drug (tsDMARD). Study participation is approximately 50 weeks, including a 6-week screening period, 24-week treatment period, and a 20-week safety follow up period.