The St. Mark's founders decided to make the school nonsectarian, with nondenominational Chapel services led by an ordained Episcopalian Chaplain. The school officially opened as St. Mark's School of Texas in 1953. The Hockaday School for Girls, founded in 1913, became the sister school to St. Mark's.
On its 40 acre-campus is an array of buildings, most of which are named after well-known Dallas families. Texas Instruments' co-founders Cecil H. Green and Eugene McDermott donated a math and science quadrangle, the main library, the greenhouse, the planetarium and the observatory.Shortly after those buildings' completion in the 1960s, Time magazine called St. Mark's the "best-equipped day school in the country."
In more recent years, the natatorium was named in honor of Ralph Rogers; the Lamar Hunt family donated a football stadium, and Tom Hicks funded a new gymnasium. The Roosevelt family contributed a carillon in 2005 and a pipe organ in 2013. The lower school has its own library, while the main library--named after Ida and Cecil H. Green--is heavily computerized but also features 56,000 volumes.
Spearheaded by a $10 million donation from the family of Harlan Crow, the Centennial Project raised over $110 million when it ended in June 2013. The Project led to 11 endowed teaching chairs as well two new state-of-the-art academic buildings. Centennial Hall houses the Math, English, History, and Administrative Departments, while the Robert K. Hoffman '65 Center--funded largely by Kenneth A. Hersh '81--houses the Language, Debate, Journalism, and College Counseling programs, in addition to the Student Store and Senior Lounge.
As of 2014, the school's overall endowment was over $100 million . Its 849 students are spread across first through twelfth grade, and the overall student/faculty ratio is 8:1. Of more than 120 faculty and administrative members, 92 have advanced degrees, including nine with doctorates. More than 30 faculty members have been at the School 20 years or more. There are seventeen endowed chairs for teaching and administration.
Over half the class of 2015 was recognized by the National Merit Scholarship Corporation, with 29 boys named as Semi-finalists and 19 boys being named commended scholars. Over the past 5 years, St. Mark's has had a higher percentage of seniors being named Semi-Finalists (28.4%) than any other school in the Dallas-Ft. Worth region. The median SAT for seniors in 2013 was 2170 on a 2400-point scale. Seven St. Marks seniors have been named Presidential Scholars by the Presidential Scholars Program since 2003. In 2013, a student also won the Nestle Very Best in Youth Award, one of 18 winners from around the country.
While many graduates stay in Texas, many also matriculate around the country. The Wall Street Journal ranked American high schools based on their sending graduates to 8 selective universities (primarily on the east coast); St. Mark's was the highest ranked Texas school in that imperfect assessment Multiple other surveys also rank St. Mark's as the top private school in the state and among the best in the country. While presumably pleased by these rankings, St. Mark's administrators have repeatedly argued that no single ranking can capture a school's excellence or its fit with any particular student.
St. Mark's organizes 17 varsity sports teams that compete against similarly-sized private schools in the Southwest Preparatory Conference.
As of 2014, the swim team had won 18 conference titles in 20 years, track and field had won 9 titles in 11 years, and wrestling had won 15 titles in 17 years; when the former wrestling coach retired in 2012, he had directed the team to 17 team state championships and 67 individual state championships. Three other St. Mark's teams have had particular success competing against both private and large public schools. For example, water polo has won five state championships, including titles in 2014 and 2015. Lacrosse and crew have also won state championships since 2010.
Fifteen alumni have gone on to play college lacrosse since 2001. Twenty three other alumni have run college track or cross-country since 1989, while a total of eighty-one St. Mark's graduates have gone on to play NCAA football. The football players include Sam Acho '07, Emmanuel Acho '08, and Kalen Thornton '00, all of whom went on to play in the National Football League the Acho brothers are currently linebackers on different NFL teams. Most recently, Ty Montgomery '11 was selected in the 3rd round of the 2015 NFL Draft by the Green Bay Packers after an All-American career at Stanford. Over the past several years, about 10% of St. Mark's graduates signed to play intercollegiate sports in college.
