The under-representation of women in undergraduate science courses is well-documented. One significant challenge is that women may both perceive and receive less recognition from their science peers about their abilities as scientists than men. Here we investigate the presence and nature of such gender biases in peer recognition in the discipline of physics specifically. First, we examine the extent to which three different instructional physics contexts exhibit a gender bias in received peer recognition by asking students to list their strong physics peers on a survey. We find that there is a gender bias (in which students disproportionately recognize men as strong in their physics course more than women) in physics courses aimed at first-year, but not beyond first-year, students. We then analyze possible mechanisms underlying this gender bias. Asking students to both nominate their strong physics peers and explain their reasons for these nominations, we find an effect of gender on what skills students are recognized for in lab, but not lecture, physics courses. In both kinds of courses, we find a strong association between peer interactions and peer recognition: of the peers with whom students interact, students disproportionately select peers of their same gender to nominate as a strong student. In the third chapter, we investigate received peer recognition over a two-semester introductory physics course sequence at a mostly-women institution. We observe that while general patterns of recognition are stable over time for the same cohort of students, the most highly nominated students are subject to fluctuations that are closely tied to changes in student outspokenness. Finally, we directly compare students' received recognition (the number of nominations they receive from peers as strong in their physics course) and perceived recognition (the extent to which they feel recognized by their peers as a physics person) across student gender. We find that for men and women receiving the same amount of peer recognition (and having the same race or ethnicity, academic year, and academic major), men report significantly higher perceptions of their recognition than women. Together, these four studies provide a strong foundation for our understanding of who and what gets recognized in physics peer recognition, with a focus on the role of gender in such recognition. This body of research lays the groundwork for future studies that design, implement, and evaluate instructional activities aimed at mitigating gender differences in peer recognition. Such interventions have the potential to retain more women and other marginalized groups in physics. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]