During World War II, Marymount students actively engaged in supporting the war effort by establishing the Marymount in Action Corps (MAC). MAC members enthusiastically participated in various initiatives, such as selling war bonds and cultivating vegetables in the Victory Garden, located where Butler Hall now stands, while also sending food and heartfelt letters to their "adopted” military units overseas.
To ensure safety on campus, heavy blackout curtains were hung around campus, and a well-equipped bomb shelter was established in the trunk room. The scarcity of silk and nylon due to shortages necessitated a change in the uniform, while transportation faced obstacles due to gas and tire rationing.
After the war, things began to return to business as usual
Butler Hall was built in 1947, providing dormitory housing for the Junior College. Later, the Junior School relocated to Brentwood, allowing the secondary students to occupy classrooms within the High School Building.
The athletics programs at Marymount grew, with students engaging in swimming and diving practices at the Beverly Hills Sand and Pool Club, as well as participating in bowling activities at an alley in Westwood Village.