Simon Gratz High School Mastery Charter, formerly Simon Gratz High School is a secondary school in Philadelphia, named after Simon Gratz (1840-1925), a member of the Philadelphia Board of Education.

Students from the previous public school's enrollment area are eligible to attend.

It is the fifth Philadelphia high school operated by Mastery.

[3] Part of the building is used for Mastery’s Prep Middle School (7-8th grade).

Gratz students are required to wear school uniforms[4] consisting of red Simon Gratz uniform shirts, black pants or black shirt, and any color shoes.