Alexander et al. give a detailed description of IgG4-related membranous glomerulonephritis (MGN). Their data delineate for the first time in IgG4-related disease (IgG4-RD) a second pattern of tissue injury occurring within the same organ. The paper highlights that MGN can occur alone or simultaneously with IgG4-related tubulointerstitial nephritis. Thus, it extends our understanding of IgG4-RD and illuminates potential pathways for new investigations into its pathophysiology.