It is clear that a number of growth factors are synthesized within the adult and the developing kidney. Compelling evidence exists that several of these agents orchestrate the nephrogenic process. A growing body of data supports roles for one or more of these agents in the adult kidney as regulators of renal function, growth, and repair processes. Growth factor expression may be the cause of glomerulosclerosis in one or more pathophysiological states. Our knowledge of the sites of growth factor synthesis and actions in the kidney and of the mechanisms by which growth factor synthesis is regulated and actions are exerted is rudimentary. Expansion of this knowledge base is likely to result in a greater understanding of renal disease mechanisms and thereby generate strategies by which kidney damage can be halted, prevented, or reversed.