According to recent scholarship, citizens in various Western democracies show a growing sense of dislike and distrust toward members of opposing political parties. While political communication processes have been shown to influence inter-party hostility, the literature has so far focused mainly on mass-mediated communication. We argue here that affective polarization might also be determined by interpersonal political communication. Specifically, we hypothesize that "heterogeneous" political discussions-those transcending partisan and ideological boundaries-are associated with decreased hostility toward the other side. We test this hypothesis with three studies conducted in Canada: A cross-sectional survey (N = 3,596), a twowave panel (N = 3,408), and an instrumental variable analysis (N = 2,005). We find that heterogeneous discussion indeed is associated with reduced polarization, a conclusion that holds across indicators of affect, obtains for both face-to-face and online discussions, and is consistent across studies. Having a heterogeneous (compared to homogeneous) discussion network predicts substantial decreases of up to 0.76, and no less than 0.09, standard deviations in out-party hostility. These findings inform scholarly debates about the antecedents of affective polarization and are consistent with the claim that cross-cutting political discussion can benefit democracy.