Western societies seem to have built themselves "against nature", as Serge Moscovici (1972) put it. According to a growing number of specialists (Parma Declaration, WHO 2010), more and more of us are suffering from "nature deficit disorder", with deleterious consequences for our health. Its corollary is the "extinction of the experience of nature" and its effects on our lack of commitment to biodiversity. Against this backdrop, which requires both support for the socio-ecological transition and careful attention to individual well-being, offering children varied experiences of nature from an early age is a key issue. Although public policies have recently become aware of this urgency, and have introduced it in several major texts in the early childhood field (e.g., in the Charter of the first 1000 days in September 2020, in the National Charter for the care of young children in 2021, in the strategy for combating and preventing poverty established in 2021), professional practices and constraints are still largely unsuited to bringing children (and the adults who accompany them) back in nature. This research-action project aims to fill this gap: it proposes an innovative approach to support early childhood professionals and parents (hereinafter referred to as "referring adults") to experience nature with young children (0-3 years), with the help of a catalog of activities, which are participatory co-constructed and validated by volunteer referring adults. A participatory platform, designed and created through the collaboration of the four project partner teams, will enable the referring adults to find inspiration, interact with each other and co-construct these early-learning practices in contact with nature. Eventually, this platform will become a pedagogical resource center, and provide a vast amount of data that can be mobilized by research to characterize the effects of nature experiences on children and on referring adults, but also on the child-adult relationship, on relations between adults and on the design of the early child caring professions. This co-research project is dedicated to the co-design and the first steps of this platform. The relationship with nature and the relationship with others being at the heart of this project, conservation sciences (at Cesco) and information and communication sciences (at Cerlis) are brought together in this highly interdisciplinary project, which aims to link the study of the semiotics of nature experience and its operational translation: proposing, collecting and sharing these nature experiences in a digital platform enabling to enlarge the participating community, to make exchanges faster, and to archive posted data. This project is initiated and co-supported by Label Vie, a association from Social and Solidarity Economy founded in 2002s and that supports early childhood facilities for ecological, social and health transition. Label Vie has always championed the major role of contact with nature in the well-being and health of young children. Through its network of almost 1,000 early childhood facilities, Label Vie has a very good practical knowledge of the early childhood and how to mobilize the professional community. Finally, the Mosaic service unit, founded in 2020 following a PIA investment; it is a partner in twenty participatory research schemes based on data co-production and sharing platforms; Mosaic will be the methodological and technical partner for this platform project.