More than a decade of research has been conducted on the ecotoxicology of manufactured nanomaterials (MNMs), or econanotoxicology. This Research Front presents a collection of papers that demonstrate that considerable progress is being made addressing the complexities of predicting the toxicity of MNMs in ecosystems. This progress is reflected in a greater awareness of the importance of environmental transformations and of methodological considerations, the use of powerful model organisms, and development of new assays and methods to predict and quantify exposure and bioavailability.