St. Mary’s Associated Student Body is an extracurricular organization whose purpose is to develop leadership and citizenship skills among SMS students, in addition to establishing a school government whereby the students cooperate with the faculty to promote student welfare and school spirit. With this purpose in mind, ASB serves to engage students in learning about democracy and leadership. As reflected in SMS Mission Statement, ASB commissioners lead by example to inspire our student body, assume leadership roles, and become active members in their school, church, and community.

SMS ASB is comprised of student representatives and officers elected from and by the student body. Offices include President, Vice President, Finance, Religious Affairs, Assembly, Publicity, Music, Boys and Girls Athletics, School Spirit, Safety & Ecology, and Altar Server Coordinator. Duties of the officers and are delineated by the School Constitution and carefully considered by all candidates before deciding to run for office. All ASB Officers are expected to be positive, supportive leaders and models for our student body.​