St. Thomas Schools is a privately-owned coeducational boarding high school, at Thiruvananthapuram in the south Indian state of Kerala. It is an English Medium School affiliated to the Council for the Indian School Certificate Examinations.

The school was established by the Mar Thoma Church Educational Society (MTCES) on 6 June 1966. It is located on a 30-acre (120,000 m) campus at Mukkolakkal, a village on the outskirts of Thiruvananthapuram city. There are distinct institutions within the campus: St. Thomas Central School, St. Thomas Higher Secondary School, St. Thomas Teachers' Training College, St. Thomas Residential School and St. Thomas Pre-primary School. The students of the St Thomas are popularly called Santhomites.

The campus has three schools inside which offers three different syllabi of examination: Kerala State Board, Central Board of Secondary Education (CBSE), and Indian Certificate of Secondary Education/Indian School Certificate (ICSE/ISC)

The school has a vast school bus system which spans over the entire city with more than 46 bus routes. The school is also known as STRS which is an abbreviated form for St.Thomas Residential School.

The school was established by the Mar Thoma Church Educational Society (MTCES) of the Malankara Marthoma Syrian Church on 6 June 1966. The Society also runs an Engineering College (St.Thomas Institute for Science and Technology) and a CBSE School (St.Thomas Public School) at its Kazhakkoottam campus and a Preschool (STPrS) at Kumarapuram. The first principal of the school was Rev. P.K. Koshy, who served as Principal from 1966 to 1968. The principals since then were

• Mr. T.Paul Varghese (1968–72)
• Mr. P.T.Mathew (1972–73)
• Mr. Thomas Mathai (1973–81)
• Mr. Thomas.P.Athyal (1981–88)
• Dr. V.M.John (1988–98)
• Mr. M.M.Mathew (1998-03)
• Mrs. Achamma Zachariah (2003–09)
• Mr. Rajan K Varughese (2009–18)
• Mr. Babykutty P Rajan (2018– )

Located on the outskirts of Thiruvananthapuram city, St. Thomas Schools at Mukkolakkal has a 32-acre campus. The school has a synthetic Turf Tennis court, a hockey field, a football ground with a 400m running track, a basketball court cum skating rink, a swimming pool, boarding hostels and a canteen.

The residential school includes a state-of-the-art Computer facility and Science labs for the students. STCS and STRS have Atal Tinkering Labs funded by the Atal Innovation Mission under Niti Aayog.

This is an inter-school cultural fest hosted by the school, which was conceptualized and started by the ISC 2007 batch and is one of the most awaited school fests each year. The final year students, supported by their teachers and their juniors, are the organizers of the event.

The full form of 'Sanrevo' is Santhomite Revolution. The motto for SanRevo 2013 was "Revive. Recreate. Rise." The fabled phoenix is the logo of SanRevo. The phoenix is 'awakened' each year for the fest. Schools from across Trivandrum participate in this annual extravaganza which is eagerly awaited.

The batches of class 11 and 12 in STRS are given special names by the students in the respective batches each year. A list of such batch names has been given below:

Batch Year	Batch Name
2007–08	---
2008–09	---
2009–10	Helios
2010–11	Hybridz
2011–12	Centaurz
2012–13	Fugitivez
2013–14	Titanz
2014–15	Renegadez
2015–16	Crusaders
2016–17	Prometheans
2017–18	Mercenaries
2018–19	Centanarians
2019–20	Krenoviantz
2020–21	Methanites
2021-22	Fintanites
2022–24	Exorianz
2023–25	Sentinels

In 2009, St. Thomas Central School started the inter school fete, Colosseum. This is also organized by 12th grade students with help from the teachers and juniors. The motto for Colosseum 2k13 was "One Team. One Dream."

Two students of opposite sex were expelled from St Thomas Central school on charge of hugging each other in school premises. Additionally, private Instagram accounts of the students were accessed to provide additional 'evidence' against students. These personal pictures of the two teenagers were described by the school as "indecent, scandalous, highly objectionable lascivious material which appeals to prurient interest." Student's parents approached the Childs Rights Commission and Kerala High Court to move against school's action. The Kerala High Court deemed the action of the school management to be legal and rejected an interim order from the Child Rights Commission that suggested the students be allowed to attend classes. School's stand is that students of opposite sex are not allowed to hug or shake each other's hands to congratulate each other and any such behavior is an act of indiscipline.

• Jassie Gift, Indian film music composer and playback singer
• Arun Kumar Aravind, Indian film director, editor and producer
• Appu.N.Bhattathiri, Kerala State Film award winning film editor
• Mr.Sadeesh Prinjukunju, Complan Boy from 2003-2007
• Chandy Oommen, MLA Puthuppally

• Official website
• Residential school site