The understanding and management of membranous nephropathy, a common cause of nephrotic syndrome that is more frequently encountered in adults than in children, has rapidly evolved over the past decade. Identification of target antigens has allowed for more precise molecular diagnoses, and the ability to monitor circulating autoantibodies has added a new vantage point in terms of disease monitoring and decisions about immunosuppression. Although immunosuppression with alkylating agents combined with corticosteroids, or with calcineurin inhibitor–based regimens, has been the historical mainstay of treatment, observational and now randomized controlled trials with the B-cell–depleting agent rituximab have moved this agent to the forefront of therapy for primary membranous nephropathy.