In recent years, universities have demonstrated heightened recognition of and concern for students' mental health by expanding mental health services as well as campus-wide mental health promotion campaigns. This article examines peer education -- a growing initiative on American campuses in which students work with their institution to create and deliver health education and awareness campaigns to their peers. I present findings from an ethnographic study including 30 interviews with student peer health educators and their supervisory staff, participant observation among three university programs, and content analysis of digital and print media created by peer educators. Using the framework of boundary objects (Star & Griesemer, 1989), I show how mental health education-and the very construct of "student mental health"- is produced in mental health promotion campaigns. As they co-construct mental health promotion initiatives, peer educators and their supervisors rely upon ambiguous working definitions of mental health that homogenize mental health challenges while individualizing their remedy through broad appeals to stress management. In this way, "student mental health" becomes synonymous with student success and retention, obscuring the shared and structural bases of student distress.