This study of a second-grade classroom in a marginalized Romani neighborhood in Spain, explores how children learn through participating in Interactive Groups (IG), a dialogic learning environment in which students dialogically solve tasks with the support of an adult volunteer. In the IG studied, volunteers were mostly Romani women with little formal education who had previously been forbidden entrance to the school. Using critical communicative methodology, data was collected through interviews, life stories, focus groups, and video recordings. Findings illustrate the unique ways in which the implementation of IGs cultivates dialogic learning. Notably, the non-expert volunteers are found to be central for that achievement: They create the conditions for fostering egalitarian dialogue and solidarity, for using cultural intelligence to access the official curriculum, and for promoting dialogue through which the students gain greater knowledge (instrumental dimension). This study expands research on dialogic teaching and learning by showing that adults from non-academic and non-dominant communities can be influential towards the success of dialogic learning classroom environments. Such central community participation also democratizes the viable affiliations between schools and vulnerable groups in Europe.