The soap and detergent industry is characterized by a highly concentrated oligopolistic market in which, according to 1970 census data, the first four companies accounted for 70% of the value of shipments and the first eight companies accounted for 79%. Price competition is limited except in the liquid detergent field. In the marketing of household products advertising plays an important role in product differentiation. On the basis of size, the industry was segmented into the first four, the first eight, 'rest of the industry' basis. Segment I company sales ranged from $400,000,000 to over one billion dollars. Aggregate plant data indicates that the efficiency of the three groups corresponds generally to their ordering. Simulation models of representative single plant producers in the industry indicate that on a point source basis the cost to the industry of the recommended control guidelines and standards is appreciable, impacting smaller producers relatively more heavily than larger producers. This point source approach is an indirect approach in assessing control costs. Since most of the industry interconnects with public waste treatment facilities, the greatest potential cost impact of effluent control will come from rising public waste treatment charges. No adverse community, employment, or balance of payment effects are anticipated. Bibliography.