This article analyzes a deliberative forum on nanotechnologies, organized in Portugal within the scope of the research project DEEPEN—Deepening Ethical Engagement and Participation in Emerging Nanotechnologies. This event included scientists, science communicators and members of the “lay public”, and resulted in a position document which summarizes collective aspirations and concerns related to nano. Drawing upon our previous experience with focus groups on nanotechnologies—characterized by methodological innovations that aimed at suspending epistemological inequalities between participants—this paper delves into the performativity of the (...) deliberative event, exploring some of the tensions and power/knowledge asymmetries generated by the forum. Recognizing that the design of participatory assemblages matters, we reflect on our role as facilitators and explore the difficulties in organizing exercises of upstream engagement with emerging technologies. (shrink)