Do academic journals favor authors who share their institutional affiliation? To answer this question we examine citation counts, as a proxy for paper quality, for articles published in four leading international relations journals during the years 2000–2015. We compare citation counts for articles written by “in-group members” (authors affiliated with the journal’s publishing institution) versus “out-group members” (authors not affiliated with that institution). Articles written by in-group authors received 18% to 49% fewer Web of Science citations when published in their home journal (International Security or World Politics) vs. an unaffiliated journal, compared to out-group authors. These results are mainly driven by authors who received their PhDs from Harvard or MIT. The findings show evidence of a bias within some journals towards publishing papers by faculty from their home institution, at the expense of paper quality.