The ON-MERRIT project aims to critically interrogate whether Open Science (OS) and Responsible Research and Innovation (RRI) live up to the positive claims of their proponents in a multitude of ways and whether the Matthew effect in academia, or other forms of cumulative advantage and disadvantage, may be present within or even exacerbated by OS and RRI practices. We set this project against the backdrop of the grand societal challenges that are reflected in the UN Sustainable Development Goals (SDGs), which imply required collaboration between research scientists, policy-makers, civil society actors and broader publics. Reflecting this context, we focus our work within this project on three relevant domains: agriculture, climate, and health. Of particular interest to ON-MERRIT Task 5.3, on which this deliverable reports, is whether OS does in fact support scientific uptake by policy-makers, and, to the second point, whether the Matthew effect or other forms of cumulative advantage or disadvantage may be at play and impacting participation in policy-making. We approach this research with recognition of the fact that, as yet, there is little empirical evidence as to the impact of OS practices on research uptake by policy-makers—a finding established by the earlier ON-MERRIT Deliverable 5.1 (Reichmann, Wieser, and Ross-Hellauer 2020). We also recognize that RRI is intended to equitably reconfigure the science-society relationship by bringing together public policy, societal relevance and effective implementation in novel ways, drawing on elaborated methods and conceptual frameworks from the long history of negotiating the science-society-relationship. To that end, researchers who conduct projects aligned with RRI principles and practices work with a broad range of societal actors to engage them in participatory practices that seek to provide a knowledge basis for policy-making. As such, these researchers are often important gatekeepers as well as enablers for engagement in participatory research. In response to these conditions, we ask two primary research questions (and two sub-questions): RQ1: What factors influence scientific uptake by policy-makers? RQ2: Which societal actors, both within and outside of academia, participate in OS and RRI research and policy-making? Which societal actors are excluded, and why? Who influences public participation in policy-making? To respond to these questions, we conducted a qualitative study composed of in-depth interviews and workshops with policy-active researchers who either practice RRI or whose research resonates with RRI practices. The participants, gathered from diverse institutions across the EU and beyond, participated in one of three workshops focused on ON-MERRIT’s three domains of interest: climate, agriculture and health. Our workshops, guided by a facilitator from our team, guided participants through three discussions, focused on 1. How to further enable the uptake of scientific research in the process of policy-making; 2. How to improve equality in representation, access and impact in policy-making in terms of individuals who have access to this sphere and in terms of whose interests are (or are not) represented; and 3. Whether OS can change the uptake of science in policy-making. Our team collaboratively coded and analyzed transcriptions of workshops and interviews and worked collaboratively with participants to co-create preliminary findings during a later workshop. Based on these findings, we conclude that while there are several key factors that influence scientific uptake by policy-makers, OS is not chief among them. Additionally, OS and RRI, as they are currently practised within the contexts of academic and scientific institutions, are not doing enough and are not yet widely enough adopted to have a significant impact on expanding equitable participation in scientific knowledge production and policy-making. Further, we conclude that the Matthew effect and other forms of cumulative advantage and disadvantage are present within both processes, and are interacting with historical systems of inequality, including racism, sexism, ageism, classism and the lingering effects of colonialism. Based on these findings, we offer selected recommendations to researchers, funders, and academic and scientific institutional leaders.