For some time, the Drinking Water Research Division has evaluated the performance, cost and feasibility of using GAC and AS for removing organic compounds from drinking water. The data collected at field locations have been used to develop and verify computer models to aid in evaluating preliminary designs of packed tower aeration and liquid-phase GAC treatment systems for removing organic contaminants in drinking water. Little additional research is being done in the field at this time evaluating treatment technologies for removing synthetic organics from drinking water. An extensive amount of field research, however, is underway evaluating control of disinfection by-products. The paper will briefly discuss the cost and performance computer models and more thoroughly discuss four research field projects for controlling disinfection by-products.