The European Commission’s (EC) Joint Research Center (JRC) recently published a JRC Science for Policy Report entitled Identification of nanomaterials through measurements that is intended to support the implementation of the EC’s Recommendation on the definition of nanomaterials (2011/696/EU). It is a follow-up of a previous JRC Science for Policy Report on concepts and terms used in the definition. The present report addresses identification of nanomaterials by measurements and discusses options and points to consider when assessing whether a particulate material is a nanomaterial, according to the definition of nanomaterials. According to JRC, the primary criterion against which particulate materials should be assessed is the median of the number-based distribution of the external dimensions of the particles. The particles to be measured are the constituent particles of the material, regardless whether these particles appear separate from one another or are parts of aggregates or agglomerates. JRC states that the main steps to identify nanomaterials by measurements are collecting information on the material, acquiring knowledge of the measurement method(s), matching method(s) and material, sample preparation, measurement/analysis, and decision (nanomaterial/no nanomaterial). JRC notes that assessing particle size measurements requires specification of the measurand, the physical principle of the measurement technique, the applied sample preparation protocol, the covered size range, and the data analysis procedure to allow a reliable classification of a material according to the EC nanomaterial definition. JRC provides examples and practical options for consideration, including a flowchart that can assist users with relevant technical knowledge in the identification of nanomaterials.