| Acronym | Definition |
|---|
| IWG | International Working Group |
| IWG | Instant Win Game |
| IWG | Interagency Working Group |
| IWG | Informal Working Group |
| IWG | Implementation Working Group |
| IWG | Interoperability Working Group |
| IWG | Independent Working Group (various organizations) |
| IWG | Integration Working Group |
| IWG | International Working Group on Women and Sport |
| IWG | Interface Working Group |
| IWG | Intelligence Working Group |
| IWG | Investigators Working Group (EOS) |
| IWG | Interactive Working Group |
| IWG | International Wenches Guild |
| IWG | Investigation Working Group |
| IWG | InterNetworking Working Group (est. 1972) |
| IWG | Insured Window Guarantees, Ltd. (UK) |
| IWG | Inches of Water Gauge (volume-flow rate) |
| IWG | Integrated Working Group |
| IWG | Information Windowing Group |
| IWG | Initialization Working Group |
| IWG | Iron-Wustite-Graphite |
| IWG | Idiots with Guns |
| IWG | Industrial Waste Group (Exton, PA; est. 1998) |