Is Facebook used to develop social capital? This question is approached here on the basis of the practices of adolescents from working-class backgrounds, met during classroom interventions and individual interviews. The starting point was to consider the construction of social capital in the age of the Web, where a plethora of contents and relationships are accessible without being introduced by parents and without geographical constraints. Despite this utopian openness, we have seen that the entanglement of heterogeneous relationships, from the family to the “exes,” and the publicity of interactions displayed on the wall lead to the risk of being “exposed.” It actually encourages adolescents to foster strong ties more than casual encounters. Likewise, the contents shared on Facebook are homogenized in order to show one’s bond with one’s peers, and curiosity can only unfold if it is backed by a passion. The platform thus blocks the possibilities of exploration and experimentation that are necessary to adolescents, and instead confirms a social place, through affinities and the convergence of tastes.