Dysproteinemic kidney diseases occur when B- or plasma cell clones produce pathogenic monoclonal immunoglobulins or light chains that cause kidney damage. The clinical presentation of these disorders ranges from sub-nephrotic-range proteinuria or microscopic hematuria with preserved kidney function to severe nephrotic syndrome to severe acute kidney injury or rapidly progressive glomerulonephritis. These monoclonal immunoglobulins can cause a variety of histologic patterns of injury, including cast nephropathy, glomerular and tubular deposition diseases, amyloidosis, and inflammatory glomerulonephritis. The underlying clonal disorder may meet criteria for overt multiple myeloma or systemic lymphoma. In recent years, there has been increased recognition and study of dysproteinemic kidney diseases that occur in the setting of smaller clonal plasma and B-cell populations, which are classified as monoclonal gammopathies of renal significance. Regardless of clonal cell burden, the goal of treatment is to achieve a hematologic response (ie, improvement or resolution of the monoclonal protein) by eradicating the underlying clone. Organ-specific responses are dependent on achieving hematologic response. Without appropriate treatment, many of these disorders are associated with high rates of progressive kidney disease and end-stage kidney disease. In this installment of AJKD's Core Curriculum in Nephrology, we review the pathogenesis, diagnosis, and treatment of dysproteinemic kidney diseases.