The optimal implementation of STEM in K-12 schools is a long-range goal, yet, currently there is no clear understanding of how STEM education is defined and how schools are implementing integrated STEM curricula. The main purpose of this study was to critically analyse themes found in major international STEM education policies and practices. The main question of the study was, what are the international common themes of effective instructional policies and practices of the STEM education? The study followed a qualitative approach with use of document analysis, incorporating Braun"s and Clarke"s protocol for selecting the key international STEM policies, reports, and documents. The thematic analysis revealed two broad classes of implementation global themes: structural and interpersonal. The structural implementation global themes include: "subject integration/project-based learning/design-based education, non-traditional assessment, STEM content, time, professional development, and outside support (e.g., businesses and industry). The interpersonal implementation global themes include: leadership, collaboration, willingness, and authentic/meaningful/relevant experiences for participants. In conclusion, the appeal of integrative policy of education calls for constructivist-based approaches that are deemed highly effective within STEM curricula because of the integrative nature of its concepts that include a myriad of constructivist practices to help build 21st-century skills within students.