| School | HMC Division | Membership | Location | Age Range |
| Stowe School | East (UK) | British Isles | Stowe, United Kingdom | 13 - 18 |
| Strathallan School | Scottish (UK) | British Isles | Perth, United Kingdom | 9 - 18 |
| Streatham & Clapham High School | London (UK) | British Isles | Streatham, London, United Kingdom | 3 - 18 |
| Sullivan Upper School | Irish | British Isles | Holywood, United Kingdom | 12 - 18 |
| Surbiton High School | London (UK) | British Isles | Kingston-upon-Thames, Surrey, United Kingdom | 4 - 18 |
| Sutton High School | South East (UK) | British Isles | Sutton, United Kingdom | 3 - 18 |
| Sutton Valence School | South East (UK) | British Isles | Sutton Valence, United Kingdom | 2 - 18 |
| Sydney Grammar School | International | International | Darlinghurst, Australia | 4 - 18 |
| Tanglin Trust School | International | International | Queenstown, Singapore | 3 - 18 |
| Taunton School | South West and Wales (UK) | British Isles | Taunton, United Kingdom | 0 - 18 |
| The Abbey School, Reading | South Central (UK) | British Isles | Reading, United Kingdom | 3 - 18 |
| The British International School, Cairo | International | International | , | 11 - 18 |
| The British School in the Netherlands | International | International | Voorschoten, Netherlands | 3 - 18 |
| The British School of Amsterdam | International | International | Amsterdam, Netherlands | 3 - 18 |
| The British School of Barcelona | International | International | Barcelona, Spain | 2 - 18 |
| The British School of Brussels | International | International | Brussels, Belgium | 1 - 18 |
| The British School of Milan | International | International | Milan, Italy | 3 - 18 |
| The British School of Paris | International | International | Paris, France | 3 - 18 |
| The British School, New Delhi | International | International | New Delhi, India | 3 - 18 |
| The Bury Grammar Schools | North West (UK) | British Isles | Bury, United Kingdom | 3 - 18 |
| The Canford Schools Group | South Central (UK) | British Isles | Wimborne, United Kingdom | 13 - 18 |
| The Cathedral School, Llandaff | South West and Wales (UK) | British Isles | Cardiff, United Kingdom | 3 - 18 |
| The Dean Close Foundation | West (UK) | British Isles | Cheltenham, United Kingdom | 2 - 18 |
| The Doon School | International | International | Dehradun, India | 12 - 18 |
| The Edinburgh Academy | Scottish (UK) | British Isles | Edinburgh, United Kingdom | 2 - 18 |
| The English College in Prague | International | International | Prague, Czech Republic | 13 - 18 |
| The English School, Cyprus | International | International | Nicosia, Cyprus | 11 - 18 |
| The Glasgow Academy | Scottish (UK) | British Isles | Glasgow, United Kingdom | 3 - 18 |
| The Global College Madrid | International | Associate (International) | Madrid, Spain | 13 - 18 |
| The Godolphin and Latymer School | London (UK) | British Isles | Hammersmith, London, United Kingdom | 11 - 18 |
| The Grammar School at Leeds | North East (UK) | British Isles | Leeds, United Kingdom | 3 - 18 |
| The Grange School | North West (UK) | British Isles | Northwich, United Kingdom | 4 - 18 |
| The Grange School, Chile | International | International | La Reina, Chile | 3 - 18 |
| The Judd School | South East (UK) | Associate (UK) | Tonbridge, United Kingdom | 11 - 18 |
| The King’s School in Macclesfield | North West (UK) | British Isles | Macclesfield, United Kingdom | 3 - 18 |
| The King’s School, Australia | International | International | Sydney, Australia | 3 - 18 |
Stowe School
Age range
13 - 18
Location
Stowe, Buckingham, MK18 5EH, United Kingdom
Head’s name
Anthony Wallersteiner
Strathallan School
Age range
9 - 18
Location
Forgandenny, Perth, Scotland, PH2 9EG, United Kingdom
Head’s name
Mark Lauder
Streatham & Clapham High School
Age range
3 - 18
Location
42 Abbotswood Road, London, SW16 1AW, United Kingdom
Head’s name
Cathy Ellott
Sullivan Upper School
Age range
12 - 18
Location
Belfast Road, Holywood, BT18 9EP
Head’s name
Craig Mairs
Surbiton High School
Age range
4 - 18
Location
13-15 Surbiton Crescent, Kingston-upon-Thames, Surrey, KT1 2JT, United Kingdom
Head’s name
Matthew Shoults
Sutton High School
Age range
3 - 18
Location
Sutton High School GDST, 55 Cheam Road, Sutton, UK
Head’s name
Bethany Dawson
Sutton Valence School
Age range
2 - 18
Location
North Street, Sutton Valence, Kent, ME17 3HL, United Kingdom
Head’s name
James Thomas
Sydney Grammar School
Age range
4 - 18
Location
College Street, Darlinghurst NSW 2010, Australia
Head’s name
Stuart McPherson
Tanglin Trust School
Age range
3 - 18
Location
95 Portsdown Road, Singapore, 139299
Head’s name
Craig Considine
Taunton School
Age range
0 - 18
Location
Staplegrove Road, Taunton, Somerset, TA2 6AD, United Kingdom
Head’s name
James Johnson
The Abbey School, Reading
Age range
3 - 18
Location
30 Christchurch Road, Reading, Berkshire, RG2 7AR, United Kingdom
Head’s name
Sarah Tullis
The British International School, Cairo
Age range
11 - 18
Location
Km 38, Cairo-Alexandria Desert Road, Beverley Hills, Cairo, Eygpt
Head’s name
Chris Hansen
The British School in the Netherlands
Age range
3 - 18
Location
Boerderij Rosenburgh, Voorschoten, 2252BA, The Netherlands
Head’s name
Louise Simpson
The British School of Amsterdam
Age range
3 - 18
Location
Havenstraat 6, 1075PR, Amsterdam, The Netherlands
Head’s name
Ciaran Harrington
The British School of Barcelona
Age range
2 - 18
Location
Carrer Ginesta 26, 08860 Castelldefels, Barcelona, Spain
Head’s name
Neil Tetley
The British School of Brussels
Age range
1 - 18
Location
Pater Dupierreuxlaan 1, 3080 Tervuren, Belgium
Head’s name
James Penstone
The British School of Milan
Age range
3 - 18
Location
Via Carlo Alberto Pisani Dossi, 16, 20134 Milano MI, Italy
Head’s name
Simon Lockyer
The British School of Paris
Age range
3 - 18
Location
38 Quai de l'Écluse, 78290 Croissy, Paris, France
Head’s name
Nicholas Hammond
The British School, New Delhi
Age range
3 - 18
Location
Doctor Jose P Rizal Marg, Chanakyapuri, New Delhi, Delhi, India
Head’s name
Vanita Uppal
The Bury Grammar Schools
Age range
3 - 18
Location
Bury Grammar School, Tenterden Street, Bury, Lancashire, BL9 0HN, United Kingdom
Head’s name
Jo Anderson
The Canford Schools Group
Age range
13 - 18
Location
Canford Magna, Wimborne, Dorset, BH21 3AD, United Kingdom
Head’s name
Chris Wheeler
The Cathedral School, Llandaff
Age range
3 - 18
Location
Cardiff Road, Cardiff, Wales, CF5 2YH, United Kingdom
Head’s name
Clare Sherwood
The Dean Close Foundation
Age range
2 - 18
Location
Shelburne Road, Cheltenham, Gloucestershire, GL51 6HE, United Kingdom
Head’s name
Areti Bizior
The Doon School
Age range
12 - 18
Location
Mall Road, Krishna Nagar, Dehradun, Uttarakhand 248001, India
Head’s name
Jagpreet Singh
The Edinburgh Academy
Age range
2 - 18
Location
42 Henderson Row, Edinburgh, EH3 5BL, United Kingdom
Head’s name
Barry Welsh
The English College in Prague
Age range
13 - 18
Location
Sokolovska 320, Prague 9, 190 00, Czechia
Head’s name
Nigel Brown
The English School, Cyprus
Age range
11 - 18
Location
1 Presidential Palace Avenue, Nicosia, Strovolos, CY-1684, Cyprus
Head’s name
Nicholas Eatough
The Glasgow Academy
Age range
3 - 18
Location
Colebrooke Street, Glasgow, Scotland, G12 8HE, United Kingdom
Head’s name
Matt Gibson
The Global College Madrid
Age range
13 - 18
Location
C. de Castellón de la Plana, 8, 28006 Madrid, Spain
Head’s name
Barry Cooper
The Godolphin and Latymer School
Age range
11 - 18
Location
Iffley Road, Hammersmith, London, W6 0PG, United Kingdom
Head’s name
Frances Ramsey
The Grammar School at Leeds
Age range
3 - 18
Location
Alwoodley Gates, Harrogate Road, Leeds, LS17 8GS, United Kingdom
Head’s name
Michael Hall
The Grange School
Age range
4 - 18
Location
Bradburns Lane, Hartford, Northwich, Cheshire, CW8 1LU, United Kingdom
Head’s name
Lorraine Earps
The Grange School, Chile
Age range
3 - 18
Location
Príncipe de Gales 6154, La Reina, Región Metropolitana, Chile
Head’s name
Kate Ingamells-Bland
The Judd School
Age range
11 - 18
Location
Brook Street, Tonbridge, TN9 2PN, United Kingdom
Head’s name
Jon Woods
The King’s School in Macclesfield
Age range
3 - 18
Location
The King's School, Macclesfield, Cheshire, SK10 4SP, United Kingdom
Head’s name
Jason Slack
The King’s School, Australia
Age range
3 - 18
Location
87-129 Pennant Hills Road, North Parramatta, NSW 2151, Australia
Head’s name
Anthony George