Among the key constituents in the contemporary smart city paradigm lie ‘smart people’ and ‘smart governance’, placing at the forefront community engagement and awareness raising with regards to current and emerging cities’ challenges; and the necessity for a steady interaction/cooperation between decision-making bodies and societal groups. Within such a context, youngsters, as a specific age group and the ‘citizens of tomorrow’, seem to be largely overlooked in the prevailing ‘for all’ urban policy stream. Taking this deficit into account and the need to embrace the young generation in the effort of designing a ‘smart and sustainable city strategy for all’, the focus of this work is on the identification of barriers to youth participation in local sustainable urban development processes. In fulfilling this goal, global and European evidence on this topic is explored, coupled with experiences gained by an urban environment in a less privileged urban area of Greece, Korydallos Municipality. Barriers to youth engagement identified at the global scene seem to apply to this specific urban environment too, while they are further enriched by city-specific peculiarities, emerging from the elaboration of two distinct participatory exercises and the use of the self-diagnosis CLEAR model.