TMI Episcopal is a private school in San Antonio. Previously known as Texas Military Institute, TMI is a selective coeducational Episcopal college preparatory school with a military tradition in San Antonio, Texas for boarding and day students. It is the sole secondary school of the Episcopal Diocese of West Texas. Founded as West Texas School for Boys, the school was later known as West Texas Military Academy, and popularly nicknamed 'West Point on the Rio Grande'; it is not located on the Rio Grande. General Douglas MacArthur attended the school.

TMI was founded in 1893 by James Steptoe Johnston, the second Bishop of West Texas in the Protestant Episcopal Church. Johnston was a native Mississippian of the planter class who had fought in twelve engagements in the Civil War, most with the Eleventh Mississippi Regiment.

Johnston's earliest name for his school in San Antonio was "The West Texas School for Boys," which was quickly changed to "West Texas Military Academy". In 1926, the name was changed to Texas Military Institute.

At the time of the school's foundation, San Antonio lay on the edge of the American frontier, with forts all along the high ground east of the Rio Grande. Johnston created a school with full-fledged military discipline, a combination unusual for Southern boarding schools.

The first rector and headmaster was Allan Lucien Burleson, a priest who had previously worked at the Shattuck School as headmaster between 1893 and 1900. The school was then largely funded by donations from wealthy residents of the eastern seaboard, many of whom had heard Johnston speak on the importance of academic and moral education for all young men. When the school first opened, there were six teachers and twelve students.

W. W. Bondurant changed the name to "Texas Military Institute" in 1926. In 1936 Bishop William T. Capers sold TMI to Bondurant, who sold the school back to the Episcopal Church in 1952. In 1926, Bondurant had merged the Upper School of San Antonio Academy with TMI. The Book of Common Prayer continued to be used in daily chapel services.

Although Bishop Johnston had, in part, intended the school to train young men for seminaries in the Episcopal Church, the school has always been open to students of any religious faith.

The JROTC, or Corps of Cadets, has been optional for girls since their admission in 1972, and for boys since 1974.

In December 2017, under the new leadership of its 31st headmaster, the Rev. Scott J. Brown, the school changed its official name to TMI Episcopal.

TMI has moved three times, each time relocating to the edge of an expanding city. The first campus was on Government Hill, next to Fort Sam Houston; the second was in Alamo Heights; and the current campus, dating from 1989, is in far northwest San Antonio, on the edge of the Texas Hill Country. The campus is modern in architecture and built almost entirely from local limestone.

The All Saints' Chapel is a 500-seat modern chapel, used for daily service of Morning Prayer and for Eucharistic services on the first Wednesday of every month as well as for quarterly school Evensongs, choral concerts and the annual baccalaureate Mass. The chapel, designed by alumnus Chris Carson of Ford, Powell & Carson, was recognized as one of the best religious buildings of 2009 by the Interfaith Forum on Religion, Art and Architecture, a knowledge community of the American Institute of Architects. The chapel organ is a two manual, 18 voice Schoenstein & Co. opus.

There are currently around 400 students, most coming from South Texas and Mexico.

Approximately one third of TMI students are members of the Corps of Cadets. The TMI Corps of Cadets is under the command of MAJ Joseph Claburn (USA, Ret.), who has been the Commandant of Cadets since the beginning of the 2019-2020 school year. MAJ Claburn served as both the Assistant Commandant and Deputy Commandant between 2012 and 2018. Cadre members CW3 Casey Reed (USA, Ret.) serves as the JROTC Army Instructor, and SFC Minnette Sandoval Cornish (USAR) serves as the Assistant Commandant in charge of Middle School Cadets. The high school leadership program is affiliated with the United States Army's Junior Reserve Officers' Training Corps. The Panther Battalion has also been named as an Honor Unit with Distinction, the highest possible unit award for a school JROTC program, for over a decade. Due to its high ranking, TMI cadets can apply for places at United States Service academies without the congressional recommendation usually required.

• Light Townsend Cummins, historian (did not graduate)
• Cresson Kearny, inventor
• David Scott, astronaut
• Lewis Sorley, historian

• Justin Blanchard, actor
• Dan Blocker, actor and producer
• Julian Onderdonk, painter

• James A. Baker Jr., attorney
• Tom Frost, banker and philanthropist

• Robert R. Brown, 9th Bishop of Arkansas
• Frank Juhan, Bishop of Florida

• Jeremy Bernard, gay rights activist
• Henry E. Catto Jr., ambassador
• Maury Maverick Jr., attorney and journalist
• George Berham Parr, politician
• Lamar S. Smith, congressman
• Milton H. West, congressman
• Bob Wheeler, member of Texas House of Representatives

• John B. Coulter, general
• Robert Gard, general
• Ralph E. Haines Jr., general
• Douglas MacArthur, Supreme Commander of the Allied Powers
• Michael L. Oates, general
• John L. Pierce, general

• Sherry Blakley, NASCAR driver
• Ross Youngs, baseball player
• Pato O'Ward IndyCar driver

• Frederick Ahl – Latinist
• Page Morris – Mathematician
• Josef R. Sheetz – General

• 1893 – West Texas Military Academy (WTMA)
• 1926 – Texas Military Institute (WTMA merged with the upper school of San Antonio Academy and the school was renamed Texas Military Institute)
• 2004 – TMI – The Episcopal School of Texas
• 2017 – TMI Episcopal (adopted in November 2017)

• Marine Military Academy
• Peacock Military Academy

• TMI website
• TMI on Twitter
• TMI on Flickr
• TMI Tube website where Residential Life students discuss their experience
• TMI on YouTube
• TMI on Vimeo