This paper discusses a AwwaRF-funded research project to summarize the issues associated with application of membranes and the effectiveness of integrating membranes with other processes and to develop a computer model to assist utilities in determining the applicability of membranes in addressing various water quality issues. a diverse cross section of membrane plants currently in operation has been closely studied. In essence, the plants varied in several aspects such as capacity, types of pretreatment, types of membranes (for example, submerged and encased), membrane chemistry, decision drivers, and geographical location. This paper presents results of more than ten in-depth case studies conducted as part of the research effort. The focus is on process selection decisions and design considerations including necessary pretreatment, hydraulics and control logic, commissioning and waste disposal options.