Each organization participating in the Äspö (HRL) International cooperation is invited to form or appoint a Modelling Team that performs modelling of HRL experiments selected by and/or suggested to the Task Force. The modelling work of such teams outside the Äspö HRL shall be supported by their respective "mother organizations". Each team may choose to model only a few experiments.
 
The Äspö Hard Rock Laboratory has so far attracted considerable international interest. As of December 2005 nine foreign organizations in addition to SKB were participating in the Äspö HRL. Six of them; Andra, BMWi, CRIEPI, JAEA, NWMO and Posiva together with SKB form the Äspö International Joint Committee (IJC), which is responsible for the co-ordination of the experimental work arising from the international participation.

The organizations participating in the HRL are:

- Agence nationale pour la gestion des déchets radioactifs, Andra, France
- Bundesministerium für Wirtschaft und Technologie, BMWi, Germany

- Institute of the Electronic Power Industry, Criepi, Japan
- Japan Atomic Energy Agency, JAEA, Japan

- Nuclear Waste Management Organization, NWMO, Canada
- Posiva Oy, Finland
- Nationale Genossenschaft für die Lagerung Radioaktiver Abfälle, Nagra,   Switzerland

- Radioactive Waste Repository Authority, Rawra, Czech Republic