Inclusion Criteria: - Patients 18 years of age at enrollment - Patients who signed an informed consent - Patients diagnosed with PsA as per the criteria of the Classification of Psoriatic Arthritis (CASPAR) Study Group17 - Patients naïve of abatacept and who at their physician's discretion initiate abatacept - Patients meeting criteria for abatacept treatment for PsA as specified in the German label Exclusion Criteria: - Patients who are currently included in any interventional clinical trial in PsA/RA Other protocol defined criteria inclusion/exclusion criteria could apply