From 2017 onwards, educational social practices will become obligatory for all students as part of every course at the University of Buenos Aires (UBA), Argentina. For a university with approximately 300 000 students, this is a major change in how higher education is understood. However, its incorporation into the curricula is but the final stage of a clear policy of extensión, developed over decades at UBA, in which the knowledge produced through research and teaching is put into the service of society. In this article, we propose that extensión can be understood as a form of relationship between the university and society, framed by a pedagogical strategy of solidarity learning and service, and implemented through mechanisms that are here called ‘educational social practices’. This article first provides an overview of the different traditions of learning and service, paying particular attention to its development in Latin America, and the emergence in this region of ‘solidarity learning and service’, or situated education. Unlike other forms of learning and service, here, the basic unit of analysis is not the individual or the learning processes, but the reciprocal action; that is, the relational nature of people acting in certain contexts. Next, the article provides a short description of the Comprehensive Community Action Program in Vulnerable Neighborhoods, UBA’s MacJannet Prize–winning program, as a means to illustrate our distinct understanding of extensión in action – relational, situational, pedagogical and the mechanisms that propel it. This successful program has served as a fertile learning ground for the university, informing our understanding of what it means to teach, research and learn. To finish, the article provides a brief overview of these mechanisms by which the university has made whole-of-university participation mandatory: striving towards connectivity, continuity and curricular and social impact.