Old Mill High School is one of the largest high schools in the state of Maryland, educating more than 2,300 students from grades 9-12. Possessing at least seven feeder schools, Severn and the surrounding areas send the majority of its children to this long-standing school of excellence.

The two-story complex possesses eight acres of roof space alone, evidence of the schools vast size. With an active PTSA and top-flight sports teams, Old Mill has a high level of school pride and community activism. Whether its raising money for the less fortunate during Thanksgiving or rallying behind the state-ranked football team, the school's size and area of influence is only lessened by the passion of its students and families.