Study to Assess Real-world Effectiveness of Belimumab for Treatment of Adults With LN

Inclusion Criteria: * Participants to provide a signed informed consent at the time of enrollment per protocol, * Male or female aged 18 or over at initiation of belimumab, * Participants received belimumab in any formulation (subcutaneous or intravenous) for the treatment of active LN prescribed as per local label in combination with standard immunosuppressive therapy/ies at initiation of belimumab, * Participants initiated belimumab 6 to 24 months prior to study enrollment, * Accessibility of medical records starting at belimumab initiation (including accessibility of medical records for the prior 12 months and confirmatory biopsy at any time prior to belimumab initiation), * Biopsy-confirmed LN diagnosis at any time prior to belimumab initiation for treatment of LN * Class III (focal LN) with or without Class V (membranous LN), * Class IV (diffuse LN) with or without Class V, * Class V. Exclusion Criteria: * Participants receiving renal replacement therapy (i.e., dialysis, kidney transplant, or those in end-stage kidney disease) at initiation of belimumab, * Participant is concomitantly receiving another SLE targeted monoclonal antibody (MAb), or a MAb expected to compromise immune responses, at initiation of belimumab, * Participants in a clinical trial during the observation period (with the exception of allowing participation in other non-interventional studies), * Participant is pregnant at the initiation of belimumab, * Participant with a kidney transplant at the initiation of belimumab, * Participants will be excluded from the study if they are planning to become pregnant or are pregnant at study enrollment.