The Guide summarizes the sources of pollution in the wool-processing industry, the polluting effects of woolen-mill wastes, and information on the methods of dealing with the waste problems of the industry. Four separate operations of the industry produce liquid wastes: opening and scouring, spinning, dyeing, and finishing. Significant polluting characteristics of these individual wastes include oxygen demand, suspended solids, acidity, alkalinity, color, and grease. The polluting effect of the wastes may be reduced by substituting detergents for soap, mineral acids for acetic, synthetic compounds for starch, and similar changes. Limiting the amounts of acids, bases, and reducing agents to the actual requirements for the process also will reduce waste loads. Wool fibers, wool grease, and fertilizer material all may be recovered from the wastes. The wastes may be treated in combination with domestic sewage, or they may be treated by (1) coagulation and precipitation with chemicals, (2) chlorination, (3) biological processes, and (4) adsorption. The information contained in this Guide can help the mill supervisor carry out his increasing responsibility to reduce the polluting effect of the mill wastes. Much can be accomplished through good housekeeping procedures which also reduce operating costs.