Horizon 2020 (H2020), the EU’s flagship research and innovation programme (2014–2020), made gender equality a cross-cutting issue, with a strong focus on integrating the gender dimension into research and innovation content. This approach was rooted in the recognition that both biological (sex) and socio-cultural (gender) differences influence research outcomes and innovation processes, and that addressing these differences enriches scientific results, enhances societal relevance, and supports responsible research. The EU’s commitment to gender equality in research has evolved from addressing the underrepresentation of women in science to a broader strategy that includes integrating gender analysis into research and innovation content. This shift was formalized in key policy documents, including the Amsterdam Treaty (1999), the Europe 2020 Strategy, and the European Research Area (ERA) Communication (2012), which established gender equality and mainstreaming as priorities for fostering scientific excellence and innovation. Horizon 2020 operationalized gender equality through three main objectives: Fostering Gender Balance in Project Teams: Promoting equal opportunities and closingparticipation gaps for women in research teams. Ensuring Gender Balance in Decision-Making: Setting targets for the underrepresented sexin panels (40%) and advisory groups (50%). Integrating the Gender Dimension in Research and Innovation Content: Requiringresearchers to consider sex and gender analysis in research questions, methodologies, andoutcomes. The implementation of the integration of the gender dimension in research and innovation content is defined in the legal and strategic framework of H2020. Specifically,, Article 16 of the H2020 Regulation mandated the effective promotion of gender equality and the integration of the gender dimension in research and innovation content, to be addressed at all stages of the research cycle. Many calls were “gender-flagged” to highlight this requirement. Applicants were required to describe in their proposals how sex and/or gender analysis was relevant to their research. The European Commission supported applicants with different documents like best practice reports, guidelines etc. providing insights and guidance on this topic. To strengthen the implementation of the gender dimension across the whole programme each thematic advisory group needed to include gender experts who provided guidance on integrating the gender dimension and monitored progress. The inclusion of the gender dimension was part of the proposal evaluation criteria, reinforcing its importance for scientific excellence and impact. H2020 distinguished between ‘sex’ (biological characteristics) and ‘gender’ (socio-cultural factors), and emphasized the importance of analyzing both to avoid bias and ensure that research benefits all segments of society. By mainstreaming the gender dimension in research and innovation, Horizon 2020 aimed to foster more inclusive, relevant, and high-quality research outcomes, while advancing the EU’s broader goals of equality and innovation-driven growth. Horizon 2020 (H2020) was the first EU framework programme to make gender a cross-cutting issue, embedding the integration of the gender dimension into research and innovation content as a core objective. This meant that applicants were encouraged—and in many cases required—to consider how sex and gender differences affect research questions, design, methodologies, and outcomes across all project stages. The rationale was that integrating gender analysis improves the scientific quality and societal relevance of knowledge, technologies, and innovations produced, leading to results that better address the needs and behaviors of both women and men. H2020 recognized that without this dimension, research risks being partial or biased, and may fail to deliver effective solutions for all users. As a result, many topics in the H2020 work programme were "gender-flagged," and the inclusion of a gender dimension was evaluated as part of project excellence, helping to drive more inclusive and impactful research and innovation across Europe.