The following organisations and institutions are full members of NWPC.
- Dansk TraeBeskyttelse
- Treindustrien i Norge
- Kestopuuteollisuus ry
- Svenska Träskyddsföreningen
NWPC may also approve other similar legal organisations, or companies, from the founding countries, as a member or associated member. Only one organisation or company from each country should be a member.
The General Assembly consists of the representatives of the Member Organisations (no more than two from each Member Organisation), who are appointed by each Member Organisation. Each ordinary Member Organisation has one vote at the General Assembly.
The General Assembly shall be held annually and extraordinary meetings can be held when necessary.
A majority vote decides at matters taken up for decision at the General Assembly. If there is an equal number of votes on each side, the vote of the chairman of the meeting will decide the matter.