Treatment options for primary IgA nephropathy (IgAN) and Henoch-Schönlein nephritis are still largely based on opinion or weak evidence. Consequently, the recent KDIGO Clinical Practice Guidelines for Glomerulonephritis have assigned low levels of evidence for almost all recommendations and suggestions related to these two diseases. In this Review, we describe an algorithm for structuring the treatment of IgAN depending on the clinical scenario. Key to therapeutic decision making is assessment of the individual's prognosis. Clinical parameters (such as proteinuria, hypertension, and impaired glomerular filtration rate [GFR]) are used to estimate risk, but the clinical value of the novel histological Oxford-MEST classification remains to be determined. If these parameters indicate a risk of progressive GFR loss, comprehensive supportive care remains the mainstay of therapy. Two large trials, STOP-IgAN and TESTING, are underway to evaluate the value of adding corticosteroids after initiating such supportive care. At present, little evidence exists to suggest that any other immunosuppressive therapy beyond corticosteroids is effective in either IgAN or Henoch-Schönlein nephritis.