Anaerobic membrane bioreactor (AnMBR) is a relatively new technology for the treatment of municipal and industrial wastewater, which has the potential to be a less energy-intensive alternative to the aerobic treatment processes. Particularly AnMBR has demonstrated its superiority over conventional anaerobic biological processes in terms of higher effluent quality for reuse and reclamation and decoupling of solids retention time from hydraulic retention time. Although the use of AnMBRs has expanded significantly in recent times and developments are ongoing, it has not been marketed to a large extent, and its design and operation have not been fully mature. At the current stage of development, AnMBR faces some research and development challenges that need to be tackled such as membrane fouling, short membrane lifespan, and requirement of easily scalable reactor design. When these challenges are addressed, AnMBR may be widely uptaken to large-scale applications, and thus a more competitive market for its applications may emerge. Currently, there is a lack of detailed design and operation guidance for AnMBR. This book chapter is to fill the gap in this area by summarizing the information of basic process design and operation of AnMBR for wastewater treatment. The basic principles and factors affecting AnMBR design and operations are systematically reviewed and discussed. It is anticipated that this chapter can serve as a general guidance for full-scale AnMBR plant process design and operation.