Despite youth organisations having participated as a recognised constituency (YOUNGO) in the United Nations Framework Convention on Climate Change (UNFCCC) for over a decade, few studies have explored their lived experiences of participation. Drawing upon deep ethnographic engagement with a member organisation of YOUNGO conducted between 2015 and 2018, this paper applies the “7P” model from the Youth Studies literature to explore youth participation in the UNFCCC from seven intersecting lenses: Purpose, Positioning, Perspectives, Power Relations, Protection, Place, and Process. This yields many insights into how youth participants negotiate sustainability in this context, including the Purposes or drivers motivating their participation, the ways in which youth are Positioned within the UNFCCC, the asymmetrical Power Relations they have to navigate, as well as the logistical challenges relating to their Protection, including their physical safety and psychological wellbeing. Based on rich empirical findings, we amend the 7P model of youth participation, replacing Process, which we argue is more of a methodological than an analytical concern, with Psychological Factors, which we propose is a key factor in shaping youth participation in negotiations of sustainability.