| Abbreviation | Definition |
|---|---|
| ISSH | International School of the Sacred Heart |
| ISSL | Independent Schools of St Louis |
| ISSL | Independent Schools of St. Louis |
| ISSL | International School of Saint Lucia |
| ISSL | International School São Lourenço |
| ISSL | International Sunday School Lesson |
| ISSL | Iowa Standards for School Leaders |
| ISSP | Integrated Safe School Plan |
| ISSP | International School System Peshawar |
| ISSRA | Illinois School Student Records Act |
| ISSSC | Independent Schools Skiing and Snowboarding Championships |
| ISSSC | International Summer School on Smart Cars |
| ISST | In School Support Teacher |
| ISTA | International School of Temple Arts |
| ISTA | International Schools Theatrical Arts |
| ISTC | Interpersonal Skills Teaching Centre |
| ISTP | International School of the Peninsula |
| ISV | Independent Schools Victoria |
| ISW | Independent School of Winchester |
| ISW | International School of Wuxi |