A Plenary meeting can be held if at least 76 MPs (half plus one of the total of 150) are present in the building of the House of Representatives. This is called the quorum. As a lot of work is done in committee meetings, it often happens that only a few seats in the Plenary Hall are occupied. Specialist issues are first discussed in a committee meeting, by the spokespersons on the subject for their political group. If the debate is continued in a Plenary meeting, they will often be the only MPs attending.
A combined meeting of both chambers of the States General is called a Joint Sitting. The President of the Senate chairs Joint Sittings. A Joint Sitting is held at the State Opening of Parliament, for instance, every year on the third Tuesday in September (Prince's Day) when the King delivers the so-called Speech from the Throne.
At the request of one-tenth of the MPs who are present, or if the President deems this necessary, the doors of the House of Representatives are closed. The House then decides whether or not the issue will be dealt with in a closed meeting. This almost never occurs.
During recess periods, for instance in the summer months or at Christmas, the House of Representatives does not assemble. During the recess periods MPs have the opportunity to prepare meetings and to examine all kind of documents and dossiers. They also use recess periods to pay working visits and to keep in touch with their voters in the country.