A Capella Groups - Trinity's varied singing groups, which perform mainly without instrumental accompaniment.

Accidentals - Trinity's all-male a capella group.

African Americans at Trinity - A history of Black peoples, organizations, and experiences at Trinity College.

Air Force Reserves Officer Training Corps - Trinity's ROTC program, in existence from 1948 until 1970.

Albert C. Jacobs Life Sciences Center (LSC) - Building on the south side of campus that houses the biology, psychology, and neuroscience departments.

Alma Mater - Trinity College's official anthem.

Alumni Association - Network of Trinity graduates working to preserve their relationship with the College.

Alumni Hall - Trinity's gymnasium, which was destroyed by fire in 1967.

Anadama Dormitory - Student dormitory that was located at 111 Crescent Street.

Archers of Washington College - A student military drill group, which originated from the Phalanx.

Arboretum - As of 2023, Trinity College is a Level 1 arboretum.

Architecture - Trinity College is the finest example of Collegiate Gothic architecture in the United States, but it is also home to other interesting and significant designs.

Asian Americans at Trinity - A history of Asian American people, organizations, and experiences at Trinity College.

Asian-American Student Association (AASA) House - A cultural house on campus meant to support students of Asian descent.

Paul D. Assaiante Tennis Center - Trinity's tennis courts, built in 2010 and named after squash and tennis coach Paul Assaiante.

Athenaeum Society - A literary and debate social organization founded in 1826.

Athletes of Color Coalition - A group formed to build community for Trinity's athletes of color.

Athletic Association - Group composed of students, faculty, and alumni that managed the school's athletic spaces and teams.

Athletics at Trinity - Trinity's competitive and leisurely organized sports.

Austin Arts Center - Building containing Trinity's fine arts based departments and spaces.