This report (Report #1) is as part of an Erasmus+ project entitled Assessment of Transversal Skills in STEM (ATS STEM), an innovative policy experimentation project being conducted across eight European Union countries through a partnership of 12 educational institutions. STEM education is a priority for all of the ATS STEM partners and each country/region is already engaged in implementing specific policy actions to promote the development of STEM knowledge and competences across their school sectors. The purpose of this first report is to provide a strong theoretical and research foundation regarding STEM Education, with particular respect to schools. The report aims to present examples of how STEM education has been defined and implemented in school curricula and how digital assessment of transversal skills and competences has been carried out.