School staff play a critical role in referring adolescents with serious emotional disturbance (SED) to mental health services; however, the mechanisms underlying this referral process are poorly understood. We used data from adolescents (N = 4365) enrolled in SAMHSA’s Children’s Mental Health Initiative Systems of Care (SOC) and participating in a national evaluation to compare the profiles of youth referred for SOC services by school staff with youth referred for those services by professionals at other agencies. We sought to identify whether school staff referred a unique set of adolescents by examining indicators of global impairment and impairment in school functioning (i.e., absences, suspensions, failures). Using multilevel regression models, we estimated the association of global impairment and school functioning with referral source (i.e., school vs. other) and controlled for SOC community characteristics and individual-level socio-demographics. Findings indicated that adolescents referred from schools had significantly lower levels of global impairment than adolescents referred from mental health settings. However, they had considerable school-related impairment, with rates of absences, suspensions, and failures that were equivalent to youth referred from most other agencies. This study is the first to examine school-related impairment among youth receiving SOC services as a function of referral source. By identifying adolescents with more mild global impairment, who nonetheless experienced significant impairment in school functioning, schools can be key contributors to effectively identifying a unique set of adolescents for SOC services. Further, schools might meaningfully inform the provision of comprehensive services to this population by educating community agencies about school functioning among youth with SED.