A variety of etiologies can lead to glomerular disease in children. Many of these diseases have variable presentations, with mild or no symptoms, while severe kidney disease can present with life-threatening complications. Therefore, it is challenging but important to diagnose specific glomerular diseases in children so that beneficial and necessary treatment can be carried out. The diagnostic evaluation of glomerular disease in children is summarized here. The evaluation of children with isolated hematuria or proteinuria from non-glomerular causes is discussed separately. Many primary diseases (kidney disease only) and secondary diseases (from systemic autoimmune diseases, vasculitis, or infections) can lead to glomerular disease. It is useful to divide glomerular disease in childhood into two main clinical types (although some disease manifestations may overlap), which allows assessment to focus on the most likely underlying disease. The initial assessment determines the type of glomerular disease, whereas the second stage of assessment depends on the initial type of glomerular disease identified (nephritic or nephrotic). Patients with the nephritic type have histological signs of inflammation with active findings on microscopic examination of the urine sediment (including erythrocytes, leukocytes, granules, and usually erythrocyte tubular and other cellular tubular patterns) and varying degrees of proteinuria. Patients with the nephrotic form have no inflammatory manifestations on histology, show proteinuria in the nephrotic range, and have inactive findings on microscopic examination of the urine sediment (only a few cells or tubular patterns).