As of 2018, St. Mark's recognized 90 extra-curricular clubs and offered 24 fine arts courses.
Academic tournaments The
debate team has won four national
policy debate titles. In addition, the team won the "world championship" at the 2015 International
Public Policy Forum. The 4-student Upper School
Quiz Bowl team won the Small School
National Academic Quiz Tournaments's National Championship in 2024 and 2025. In both years, the school’s B and C teams finished in the top 20 nationally. Teams from St Mark’s had earlier won that competition in 2017, 2021, and 2022. In 2023, competing against public and private high schools of any size, the 5-student St. Mark's team finished 5th at the PACE National Scholastic Championship in Chicago and 8th at the High School National Championship Tournament in Atlanta. For the 4th consecutive year, the 2023-24 SM 4th grade class finished 1st nationally in the most competitive division of the WordMasters Challenge, a series of 3 tests taken annually by 125,000 4th graders around the country. The tests focus on vocabulary, analogies, word usage, and critical thinking. In both 2023 and 2024, an SM 4th grader finished first nationally and a total of 7 other students finished within the top 15 in those 2 years. SM 4th grade classes had also finished 1st nationally in the 4 years between 2015 and 2018. In 2025, an SM 8th grader won the MathCounts Middle School National Championship in Washington, D.C. A total of 65,000 students participate in this competition each year. In 2003 and 2019, respectively, an St. Mark's middle schooler won the
Scripps National Spelling Bee. In the more recent competition, a 7th grader tied for first when the tournament organizers ran out of words for the students to spell. In 2025, a team of four SM students placed second in the most competitive Economics Bowl division at the Northwestern Economics Tournament. They also advanced to the international semifinals of the Harvard Pre-Collegiate Economics Challenge, achieving one of the highest average scores in the history of the competition on the written exam portion. That same year, the team finished fourth overall out of 428 teams with 2,508 competitors from 47 countries at the World Economics Cup, finishing second in the United States.
School publications All five 2022-23 St. Mark's publications earned Gold Crowns from the
Columbia Scholastic Press Association, an honor that goes to six to sixteen publications per category in the country. It was the 20th consecutive for
The ReMarker, the newspaper, extending the school's national record for winning this award, which is given to only 6 high school newspapers each year.
The Marque, the school's literary magazine, won its 9th Gold Crown in 10 years. In the category of "Special Interest Magazines", St. Mark's publications won two of the six Gold Crowns awarded in 2021-22; these awards were the 4th straight for
Focus and the 3rd straight for
Scientific Marksman. The
Marksmen, the St. Mark's yearbook, won its 8th Gold Crown, overall, but its first since 2013. In 2019, the middle school magazine won its 3rd consecutive Gold Crown, an award given to only 1 or 2 publications in the country. In 2023,
The ReMarker won a
National Pacemaker Award, the top award from the
National Scholastic Press Association; as of 2023, the newspaper had won this award 15 of the prior 19 years. SM's
Scientific Marksman was one of 6 specialty magazines in the country to win a 2023 Pacemaker, while
The Marque, was one of 6 literary magazine winners. In 2022, SM's
The Focus was one of 2 specialty magazine to win the NSPA's top award, its 4th consecutive Pacemaker. In 2025, the mini-Marque, the middle school's literary magazine, was the only middle school publication in the country to win a Pacemaker. St. Mark's seniors were named journalist of the year in the state of Texas for eight consecutive years (2013–2020) by the NSPA. In 2019, a senior was named NSPA's national journalist of the year; he became the fourth St. Mark's student in 7 years to rank among the country's top three high school journalists. For the 15th time in 16 years, 2022 St. Mark's Photography was named "Top Program" in the annual contest sponsored by the Association of Texas Photography Instructors. The contest annually draws about 7000 entries from about 90 schools.
Arts In 2021, the Texas Commission on the Arts named a SM student the state
poetry champion through its
Poetry Out Loud recitation competition. In 2016, the
President's Committee on the Arts and Humanities named an St. Mark's senior one of the 5 National Student Poets, selected from over 20,000 applicants. Between 2015 and 2017, four St. Mark's students won top awards for design from the nationwide
YoungArts competition. In addition, seventeen St. Mark's students were finalists in that YoungArts competition between 2009 and 2018. Since 2010, multiple St. Mark's students have had their films selected for inclusion in the
SXSW film festival. One student had his work profiled in
Popular Photography magazine.
Other In 2014, a St. Mark's student won the national high school chess championship and also became the youngest chess
international grandmaster in the Americas. Two other St. Mark's students have earned
National Master status while still in high school (in 2012 and 2016). In 2024, a SM senior won the
Princeton Prize in Race Relations, an award that goes to 29 high school students in the country each year. In 2012, a student earned seventeen of Scouting's Palm Awards in addition to earning the Eagle Scout rank (a feat achieved by two dozen boys in the history of Scouting). ==Notable alumni==