Automation is ubiquitous in modern complex systems, and commercial nuclear-power plants are no exception. Beyond controlling the plant's functions and systems, automation is applied to a wide range of other functions, including monitoring and detection, situation assessment, response planning, response implementation, and interface management. Automation has become a "team player" supporting personnel in nearly all aspects of operating the plant. In light of its increasing use and importance in new-and future-plants, guidance is needed to enable the NRC's staff to conduct safety reviews of the human factors engineering (HFE) aspects of modern automation. The objective of our research that we describe in this report was to develop guidance for reviewing the operator's interface with automation. We first characterized the important HFE aspects of automation, based on how it is implemented in current systems. This description had six dimensions: Levels of automation, functions of automation, processes of automation, modes of automation, flexibility of allocation, and reliability of automation. Next, we reviewed literature on the effects of all of these aspects of automation on human performance, and on the design of human-system interfaces (HSIs). Then, we used this technical basis established from the literature to develop guidance for reviewing designs. It consists of the following seven topics: Automation displays, interaction and control, automation modes, automation levels, adaptive automation, error tolerance and failure management, and, HSI integration. In addition, we offer our insights into the automationdesign process, operator training, and operations. v ACKNOWLEDGMENTS This research is sponsored by the U.S. Nuclear Regulatory Commission. The views presented represent those of the authors alone and not necessarily those of the NRC. The authors wish to thank Stephen Fleger, the NRC Project Manager, and former Project Managers, Mike Boggie and Niav Hughes for their guidance and input during this research project. We are grateful to Val Barnes for her insights and helpful comments on the report. We also thank Avril Woodhead for her technical editing of this report and Maryann Julian for preparing the manuscript.