Nephritis is a common complication of systemic lupus erythematosus (SLE) for which current therapies often prove inadequate. Current lupus nephritis classification systems emphasize glomerular acuity and scarring. However, tubulointerstitial inflammation (TII) and scarring are much better predictors of progression to renal failure. It is now becoming clear that the immunological features, and probable underlying mechanisms, are very different in lupus glomerulonephritis (GN) and TII at time of biopsy. While GN is a manifestation of systemic autoimmunity, TII is associated with local, in situ adaptive immune cell networks predicted to amplify local inflammation and tissue damage. In addition, poorly defined networks of innate immune cells and effectors likely contribute to the severity of local inflammation. Understanding these in situ immune mechanisms should lead to a better understanding of prognostically meaningful lupus nephritis subsets and reveal novel therapeutic opportunities.