This report is the result of a technical workshop sponsored by the Consumer Product Safety Commission (CPSC) and co-hosted by the National Nanotechnology Initiative (NNI) on July 7 and 8, 2015, in Arlington, VA. The main goals for the workshop were to (1) assess progress in developing tools and methods for quantifying exposure to engineered nanomaterials (ENMs) across the product life cycle, and (2) to identify new research needed to advance nanotechnology environmental, health, and safety exposure assessment for nanotechnology-enabled products.