School-based health centers (SBHCs) positively influence student health. However, the extent to which these benefits are actualized varies across sites. We conducted focus groups with high school students and teachers at an underperforming SBHC to identify facilitators and barriers to student access to SBHC services. Our qualitative analysis revealed four main emergent categories: (1) students' knowledge of SBHC services; (2) teachers' perceptions of, and experiences with, the SBHC; (3) accessing and utilizing SBHC services; and (4) student and teacher suggestions to improve the school-SBHC relationship. Our findings suggest that the relationships between health center staff and teachers are crucial and can be damaged with poor implementation. Additionally, there was a general lack of knowledge about the procedures for accessing services at the SBHC. Participants provided recommendations, including strategies for better outreach and engagement with teachers and students, as well as operational strategies to enhance communication systems and the physical environment.