A fair peer review process is essential for the integrity of a discipline's scholarly standards. However, underrepresentation of scholarly groups casts doubt on fairness, which is currently raising concerns about a gender bias in the peer review process of premier scholarly journals such as the American Political Science Review (APSR). In this study we examine gender differences in APSR reviewing during the period 2007-2020. Our explorative analysis suggests that male reviewers privilege male authors and female reviewers female authors, while manuscripts reviewed by both male and female reviewers indicate fewer gender bias. Using within manuscript variation to address confounding effects, we then show that manuscripts reviewed by both male and female reviewers receive a more positive evaluation by female reviewers in terms of recommendation and sentiment, while they experience a marginally longer duration. Because these effects are not specific for type of authorship, we recommend that invitations should reflect mixed compositions of peers, which may also avoid overburdening an underrepresented group with review workload.