This paper is intended to document the move to low-polluting practices by enterprises in response to the global problem of stratospheric ozone depletion. The Montreal Protocol, an international agreement, sets a specific timetable for the phaseout of chlorofluorocarbons (CFCs) and other substances that deplete the ozone layer. The paper examines some of the alternatives developed to date to decrease or eliminate use of these substances. In separate chapters, the paper examines alternatives to ozone-depleting substances in aerosols, as solvents, in foam-blowing, in refrigerators and air conditioners, and in fire-extinguishing, together with their associated costs. In aeorosols, the trend has been to substitute with hydrocarbons, other pressurized gases, or new devices that eliminate the need for a propellant. In most cases, switching to hydrocarbons has zero or negative incremental cost, as investment costs are offset by savings from the lower cost of hydrocarbons. In solvents, many substitutes have emerged, including aqueous and semi-aqueous solvents and substitute organic solvents, as well as new processes that eliminate the need for solvents altogether. In many cases, the cost implications are negligeable. In foam-blowing, many manufacturers are following a stepwise reduction strategy by switching to use of less CFC, and then to substances with lower ozone-depleting potential (ODP), followed by zero-ODP substances. The substitute coolant of choice in new domestic refrigerators and mobile air conditioners appears increasingly to be HFC-134a. In fire-extinguishing, there are no "drop-in" substitutes; rather, reduction can be attained in most applications by switching to "conventional" fire-protection methods such as sprinklers, carbon dioxide, foams, and dry-powder systems. Overall, the paper finds, response has been impressive, and workable substitutes or alternative methods are being or have been developed for most applications. In addition, the costs appear not to be prohibitive and, in some cases, the alternatives even result in cost savings.