IEP can refer to:
- Science and technology
- Immunoelectrophoresis, electrophoresis based separation methods for proteins
- Integrated Electric Propulsion, a type of marine propulsion
- Isoelectric point, the pH point at which an entity has no net charge
- Education and research
- Individualized Education Program, an education plan for a disabled child (USA)
- Institut d'études politiques, a group of French university faculties concentrating mainly but not exclusively on political science
- Institute for Economics and Peace, a global non-profit research organization
- Institute for Political Studies - Catholic University of Portugal, a Portuguese research institute mainly dedicated to political science
- Internet Encyclopedia of Philosophy
- Other
- Intercity Express Programme, early 21st century procurement program for high speed trains for the UK
- Irish pound, the ISO 4217 code for the former currency of Ireland