This state-of-the-science review was undertaken to identify fate and transport models and alternative modeling approaches that could be used to predict exposure to engineered nanomaterials (ENMs) released into the environment, specifically, for aquatic systems. The development of modeling frameworks that represent the unique complexities of ENM behavior in the environment is in its infancy, and a critical mass of researchers actively engaged in model development efforts has yet to be achieved. Further, it is widely recognized that there are many obstacles to model development and, in general, to conducting environmental risk assessments of ENMs that provide meaningful information for risk managers. Nevertheless, the U.S. Environmental Protection Agency (EPA) will be required to manage potential risks across the life cycle of ENMs, from production through the disposition of wastewaters and residuals containing ENMs. Therefore, this state-of-the-science review included traditional modeling frameworks as well as approaches that are considered relatively new to environmental modeling science and risk management (e.g., adaptive management, multi-criteria decision analysis).