<p>Background Despite rapid expansion of school-based behavioral health (SBBH) services, little is published about the structure, workforce, and delivery of Tier 3 SBBH programs. This limits the ability of school districts and policy makers to plan, fund, and sustain mental health services for students. To address this gap, this study assessed Tier 3 SBBH services in school districts in the United States. Methods School district officials completed a brief electronic survey assessing Tier 3 SBBH characteristics, including the presence/absence of support services, delivery modality, provider type and employment status, and funding mechanisms. Results were coded, summarized, and stratified by Health Resources and Services Administration (HRSA) region. Results The majority of school districts (n = 275/332; 83%) offered Tier 3 SBBH services. Services were most commonly offered in-person only (70%), followed by hybrid models (29%), and telehealth-only (1%). Provider composition varied by delivery modality such that hybrid and telehealth models were more likely to include psychiatrists and advanced practice providers, while in-person models relied primarily on social workers and mental health counselors. Regional variability was observed in both service availability and delivery modality. Conclusions Support for the expansion of SBBH services is critical given the current state of the youth mental health crisis. Although Tier 3 services are widely available, variation in the composition of the SBBH workforce and predominant reliance on telehealth for access to psychiatric prescribers underscores the need for policies that support nationally regulated Medicaid billing for school-based services, sustainable funding mechanisms, and reduced interstate licensure barriers for telehealth-delivered psychiatric care.</p>