Wetting and voiding dysfunction in children represent a wide spectrum of disorders ranging from uncomplicated nocturnal enuresis, which is not associated with significant uropathology, to more complicated functional voiding dysfunction, which, in the worst of cases, can result in severe deterioration of both bladder and renal function. A complete understanding and thorough evaluation of these clinical entities allow a classification that lends itself to rational and tailored therapy. Optimal response rates can be achieved only with a disciplined and well-defined approach to the evaluation and management of these children.