Mater Dei is an elementary school for boys grades 1 through 8, conducted by Catholic laymen, in Bethesda, Maryland.

[3] It opened with 55 students at a campus on Churchill Road in Silver Spring, Maryland, but moved to its present location in 1964, having expanded to 172 students.

Once elected, Edward Bennett Williams stepped down in order to give his spot to a woman by default.

[5] His son, Edward "Ned" Williams, later became Mater Dei's headmaster.

[6] During the 2018-19 school year, Mater Dei's 230 students were 91% white, 6% black, 2% Asian, 2% Hispanic, and 1% multiracial.