Upper Darby High School

Upper Darby High School (UDHS) is a four-year public high school located in Upper Darby Township, Pennsylvania, United States, as part of the Upper Darby School District. UDHS is also the oldest high school in Delaware County, PA, having been established in 1895. It is adjacent to Drexel Hill.

As of the 2010-11 school year, the school had an enrollment of 3,762 students and 256.85 classroom teachers (on an FTE basis), for a student-teacher ratio of 17.0. The population is diverse, with over 55 nationalities of students. It has a long-established football rivalry with Monsignor Bonner High School, located less than a block away. UDHS was part of the inspiration for Upper Darby alumna Tina Fey's movie comedy Mean Girls. The mascot of Upper Darby High is the Royal, which is portrayed as a male lion. In previous years, it was a court jester. The school emblem is the royal oak tree, the yearbook is named the Oak, and the newspaper is called the Acorn.

According to a report by the Pennsylvania Department of Education, 4 teachers were rated "Non‐Highly Qualified" under No Child Left Behind. Upper Darby Senior High School is one of the largest high schools in Pennsylvania by enrollment. The High School is also home to the Upper Darby Performing Arts Center, and the Summer Stage program.