Although the neonatal kidney indeed may be a functionally imperfect organ, intuition, prejudice, and a knowledge of evolution lead us to expect otherwise. The alternative possibilities proposed here are largely unproven but would seem to be a plausible synthesis of renal growth, function and stimulatory factors into an efficient system for the support of optimal growth. Although quantitatively the infant may be limited in his capacity to respond to abnormal stresses, such as in states of disease, it would seem axiomatic that the kidney functionally must be ideally suited to meet the needs of the healthy infant. Most important is the realization that adult levels of glomerular filtration, tubular reabsorption, and ratios between the two may be, and theoretically should be, inappropriate standards for the infant. As research in developmental nephrology and in pediatrics in general moves from a static, descriptive approach to a dynamic, physiological one a multitude of exciting and crucial questions await investigation.