Belgium - diplomas, references, recommendation or proof of good conduct

Do I need to send diplomas with my application?

No, they are usually not required at this stage. However, they may need to be submitted when signing your contract, so have a translated diploma ready

Should I supply references, letters of recommendation or proof of good conduct?

References or letters of recommendation are not used in Belgium. They may be requested, but this does not happen often. Proof of good conduct may be required for certain jobs.