The GRACIOUS project has developed a highly innovative science-based framework that supports the assessment of risk posed by the ever increasing array of nanomaterials on the market and under development. The framework streamlines the process for assessing their risk by logically grouping nanomaterials thereby allowing extrapolation between (read-across) nanomaterials and reducing the need to assess exposure to and toxicity on a case by case basis. The Guidance in a Nutshell gives users new to the topic of grouping of nanoforms a brief introduction to the essential elements of the Framework.