Statistics suggest that 1 in 9 Americans will be affected by kidney disease. Effective treatments remain limited, and progression to kidney failure leaves only two options: dialysis and transplant. Common to the majority of kidney disease cases, irrespective of cause, is the compromise of nephron function. Nephrons are the workhorses of the kidney and their number is set prior to birth; no new nephrons are ever formed. Therefore, any compromise in the number of functional nephrons-whether due to acute injury, genetic mutations, premature birth, developmental insufficiencies, or aging-increases the susceptibility to kidney disease. A thorough understanding of how the nephron and its specialized cell types form, function, and respond to disease will be essential for developing novel therapeutics and employing regenerative strategies.