| Abbreviation | Definition |
|---|---|
| IRWC | Institute of Roofing Waterproofing Consultants |
| ISA | Institute for Self Actualisation |
| ISA | Institute Of Self Actualization |
| ISAAC | Institute for the Study of Asian American Christianity |
| ISAE | Institute for Studies and Economic |
| ISAE | Institute for the Study of American Evangelicals |
| ISAM | Institute for Studies in American Music |
| ISAR | Institute for the Study of Academic Racism |
| ISARS | Institute for Space Applications and Remote Sensing |
| ISAS | Institute for South Asian Studies |
| ISB | Institute for Systematic Botany |
| ISBI | International Savings Banks Institute |
| ISBL | Institutions Sans But Lucratif |
| ISBM | Institute for Systems Biology Moscow |
| ISBO | Institute of Sustainable Business and Organizations |
| ISBP | Institute for Sustainable Business Practice |
| ISBR | Institute for Scientific and Biblical Research |
| ISBR | Institute of Speleology Bucharest Romania |
| ISBS | Institute for Social and Behavioral Science |
| ISC | Institute for Strategy and Competitiveness |