Malta belongs to the European Union and is also a full Schengen member state.
The citizens of Schengen member states do NOT need a visa to enter Malta.
A visa will be required for the participants coming from the countries listed on the Maltese Ministry of Foreign Affairs.
If you need an official Letter of Invitation from the conference organizers in order to obtain a visa, you should request one at the time of registration through the online process (online shortly).
For all details on getting a visa, please refer to the web site of the Maltese Ministry of Foreign Affairs.