In February 2020, CESAER published a position paper (CESAER, 2020) expressing its support for further strengthening of Open Science and Open Access in Horizon Europe. The importance of Open Access publishing of conference materials was explicitly mentioned due to its importance to universities of science & technology (S&T). As a follow-up to this position, this paper explores the current workflows around making conference papers in the Engineering disciplines openly available at a number of CESAER Member institutions. Recent initiatives aimed to make Open Access the default scholarly communications standard (e.g. the Plan S initiative) have mostly put emphasis on journal research articles, but conference papers and proceedings are also a key research output at the universities of S&T united in CESAER. This papers explores how large the fraction of conference papers is against the total number of research outputs, how often they are being published Open Access and what actions may be envisioned to increase their accessibility and mid- and long-term visibility. An analysis of the institutional research outputs for CESAER Member institutions involved in this study shows that roughly 40% of the publications at universities of S&T are conference papers, while the remaining 60% are research articles in journals and periodicals (based on the Web of Science Core Collection). The paper argues that the relevance of these conference papers for specific fields in the engineering disciplines like Computer Science and Electronic and Electrical Engineering cannot be overstated underlining the importance of addressing this area. By comparing the amount of publications stored in institutional systems against those indexed in international literature databases, the analysis highlights the very real prospect of these conference papers becoming ‘lost in space’', i.e., not being indexed or made openly available anywhere. Even if an expanded, more comprehensive version of many of these conference papers may eventually be published as journal articles, this absence of references even at a metadata level for the original conference papers means a real risk of wasted research, a loss in citations and several missed opportunities for collaborations with non-academic partners including industry. This paper further explores whether a more effectively applied policy for making these research outputs openly available at institutional repositories might be a good strategy to ensure the findability and discoverability, even after conference websites expire or are taken down. Several recommendations are suggested for institutions hosting conferences of their own, and for authors of the conference papers, towards establishing a shared understanding of what the rights of authors are in terms of openly sharing at least the full-text of accepted manuscripts. The paper calls on research funding and performing organisations, notably including the members of cOAlition S, to make a dedicated effort to ensure that conference outputs follow the same high-standard publishing workflows that apply to journal articles, including the issuing of persistent identifiers and clear policies by conference organisers regarding the authors’ rights to disseminate them via their institutional systems. This notably includes applying the rights retention strategy for conference outputs. Concretely, researchers who wish to deposit their author-accepted manuscript in a repository with an open license (e.g. CC BY), and without any embargo, must always be able to do so, including for peer-reviewed conference papers and proceedings.@en