Traditionally, ideal cotton (Gossypium ssp.) fibers are said to be as white as snow, as strong as steel, as fine as silk and as long as wool. It is difficult to incorporate these specifications favored by cotton processors into a breeding program or to set them as quantitative goals for cotton producers. Since the early 1980s in the USA, the USDA-AMS cotton classing offices have become the primary connection for fiber quality between cotton producers and processors. The high volumes of cotton passing through the classing offices every year have forced workers there to make compromises for the sake of speed and productivity, and to develop rapid, semiautomatic classing techniques that have blurred some fiber-quality definitions in ways that may favor one industry segment over another. The vertical integration of the U.S. cotton industry from field to fabric depends on efficient use and cooperative refinement of the existing line of communication. Fiber-classing technologies now in use and under development and evaluation allow quantitation of fiber properties, application of improved standards for end-product quality, and, most importantly, creation of a fiber-quality language and a system of fiber-quality measurements that can be meaningful and useful to producers and processors alike. A cotton physiologist working in production research examines the interface between cotton production and processing in terms of the fiber properties currently quantified by the USDA-AMS cotton-classing offices, describes the measurement protocols available, and investigates possible environmental sources of the significant variations in fiber quality that reduce grower and processor profits. The interaction of growth environment, genetic potential, and fiber properties quantified at harvest are discussed where appropriate data or references exist.