Background: School-based health centers (SBHCs) provide health care to vulnerable youth. The purpose of the study was to identify characteristics of youth who use SBHCs with the highest frequency to understand their health needs and receipt of health services. Methods: This study examined cross-sectional survey data from adolescents in 3 urban school districts (n = 2641) to identify the characteristics of youth who use SBHCs with high frequency (10+ visits). Analyses included calculations of simple frequencies and percentages, chi-square tests of significance and multivariate regression. Results: High-frequency SBHC users were more likely to have seriously considered attempting suicide (adjusted odds ratio [AOR]: 3.2), be sexually active (AOR: 6.8), and have been victimized at school (AOR: 2.2) compared to their peers who did not use the SBHC. High-frequency SBHC users were also significantly more likely than their peers to report "always" getting mental health (AOR: 7.0) and sexual health (AOR: 6.6) care when needed, and having talked with a health care provider about their moods/feelings (AOR: 3.1) and how school is going (AOR: 3.2) in the past year. Conclusions: These findings hold important relevance to demonstrating the value of SBHCs in increasing vulnerable youth's access to health care, particularly in urban settings.