Objective A comprehensive study on the development of political trust is absent. Studies on the socialization effect of the media generally neglect the influence of the media system. This study aims to fill this gap. Methods Using a within‐country comparison of two media systems, I estimate the influence of different socialization agents on the development of political trust through hierarchical models of repeated measurements on a representative panel of Belgian adolescents (BPPS 2006–2011, n = 3,025). Results News consumption and a public service broadcasting preference foster political trust within diverse media systems. The socioeconomic status and level of political discussion in the family, an open classroom climate, and classroom instruction about politics also promote political trust. Conclusions Television, the family, and the school are all equally important agents in the development of political trust. It is critical to take the nature of the media system into account when studying how the media affect political trust.