Despite more aggressive treatment of diabetes, hypertension, and hyperlipidemia, the incidence and prevalence rates of end-stage renal disease (ESRD) continue to increase worldwide. The likelihood of developing chronic kidney disease in an individual is determined by interactions between genes and the environment. Familial clustering of nephropathy has repeatedly been observed in all population groups studied and for multiple etiologies of kidney disease. A three- to nine-fold greater risk of ESRD is observed in individuals with a family history of ESRD. Marked racial variation in the familial aggregation of kidney disease exists, with high rates in African American, Native American, and Hispanic American families. Disparate etiologies of nephropathy aggregate within African American families, as well. These data have led several investigators to search for genes linked to diabetic and other forms of nephropathy. Evidence for linkage to kidney disease has been detected and replicated at several loci on chromosomes 3q (types 1 and 2 diabetic nephropathy), 10q (diabetic and nondiabetic kidney disease), and 18q (type 2 diabetic nephropathy). Multicenter consortia are currently recruiting large numbers of multiplex diabetic families with index cases having nephropathy for linkage and association analyses. In addition, large-scale screening studies are underway, with the goals of better defining the overall prevalence of chronic kidney disease, as well as educating the population about risk factors for nephropathy, including family history. Given the overwhelming burden of kidney disease worldwide, it is imperative that we develop a clearer understanding of the pathogenesis of nephropathy so that individuals at risk can be identified and treated at earlier, potentially reversible, stages of their illness.