The IANUS project strengthens warranted trust in science by fostering participation in research as a co-creative and inclusive process, sensitive to societal values, concerns and needs. Trust must be inspired by transparency and trustworthiness of knowledge production, and anchored by actively involving and serving society, as part of the modus operandi of science. Our core objectives: (a) Enable citizens and stakeholders to distinguish valid from unfounded trust; (b) Enable them to deal with the uncertainties and epistemic pluralism inherent in scientific knowledge; (c) Enable researchers to foster trust through radical methodological change, making research inclusive, transparent and responsive to societal needs and concerns, lowering barriers between research and society; (d) Enable researchers to conduct relevant, engaged and value-driven research while foregoing partiality, ideological biases and conflicts of interests. The acronym IANUS refers to the deity Janus of gateways (ianus in Latin), looking both at the inside and at the outside of the knowledge production process. Trust in science is never a given. Robust trust is well-placed, reciprocal and informed. Building on insights and results from other projects funded under Framework Programmes, IANUS will (a) map the landscape of projects and discourses relevant for trust in science; (b) develop its conceptual framework; (c) conduct participatory research into conditions of trust in science; (d) initiate concrete actions for strengthening trust through co-creation and engagement; (e) provide policy recommendation to key stakeholders in science and society (e.g. funding bodies, universities, research teams, educators, media); (f) create platforms for interaction and engagement between scientists and societal stakeholders to foster trust. The complexity and urgency of societal challenges has rapidly intensified, and trust in science determined our ability to address these challenges effectively.