Increasingly, youth experiencing mental health crises present to acute care medical hospitals and "board" on medical units due to inpatient psychiatric bed shortages. We conducted a retrospective cohort study of children experiencing mental health boarding at a US children's hospital from October 2020 to September 2022. We examined associations between patients' characteristics and their disposition and outcomes. Our cohort included 1891 boarding hospitalizations: 53.9% transferred to an inpatient psychiatric hospital and 46.1% discharged home. Characteristics associated with not being transferred to an inpatient psychiatric hospital included age <13 years (adjusted odds ratio aOR 0.6; 95% confidence interval CI: 0.4-0.7), disruptive or aggressive behavior (aOR 0.6; 95% CI: 0.4-0.8), psychosis (aOR 0.5; 95% CI: 0.3-0.8), COVID-19 infection (aOR 0.3; 95% CI: 0.2-0.6), or a complex chronic medical condition (aOR 0.8; 95% CI: 0.6-1.0). Our findings suggest that certain populations of children experiencing mental health boarding face disparate access to inpatient psychiatric care.