Inclusion Criteria:  American College of Rheumatology (ACR) or European League Against Rheumatism (EULAR) confirmed diagnosis of rheumatoid arthritis (RA). Moderate RA (defined by National Institute for Health and Care Excellence [NICE] as 28-joint Disease Activity Score [DAS28] C-reactive protein [CRP] >3.2 and ≤5.1) or severe RA (defined by NICE as DAS28 CRP >5.1) at the time of enrollment. Prescribed upadacitinib in line with marketing authorization. Decision to treat with upadacitinib has been made independently and prior to enrolment in the study. Able to read and understand English. Willing and able to participate in the collection of patient-reported data via mobile app.  Exclusion Criteria:  First dose of upadacitinib received prior to enrollment in the study (same day permitted) or more than 28 days after enrolment into the study. Previously received >1 biologic disease-modifying antirheumatic drugs (bDMARD) (1 switch to a biosimilar for non-clinical reasons is allowed) or any Janus kinase (JAK) inhibitor for the treatment of RA. In the opinion of the treating clinician, participant symptoms are predominately being driven by fibromyalgia or unrelated pain component instead of underlying inflammatory disease. Participation in any interventional clinical trial within the 3 months prior to initiation or at any point during the study observation period.