This lecture is based on my longitudinal research engagement with the Long Term Ecological Research (LTER) networks. I will reflect back on how I have constructed the ethnographic field and object of inquiry since 2002 and across multiple organizational, institutional and geographic boundaries. With my combined interest in ethnographic inquiry into participants everyday practices and participatory design approach for intervening, I recount how data and infrastructure came to matter in various ways, for example as information management, growing one’s own infrastructure and research infrastructure formation. From this background, I speak to ‘tight integrations’ of ethnography and participatory/collaboratory design and to extending the traditionally short-term and small-scale scopes of Participatory Design and Computer Supported Collaborative Work by ethnographically pursuing the sociotechnical phenomenon in question. Building on the work by Susan Leigh Star, Geoffrey C. Bowker and colleagues, I propose to study infrastructuring as it emerges through the dimensions of relational, invisible, connected, emerging and accreting practices, and through intervention and intentionality. I will end with some observations and experiences from our most recent investigation on the formation of pan-European research infrastructures for environmental research.