The Alkmaar Regionaal Archief keeps the archives and documentary collections belonging to 15 municipalities and encourages as many people as possible to make use of them.

At the moment, the following municipalities participate in the Regionaal Archief: Alkmaar, Anna Paulowna, Bergen, Castricum, Graft-De Rijp, Harenkarspel, Heerhugowaard, Heiloo, Langedijk, Niedorp, Schagen, Schermer, Wieringen, Wieringermeer and Zijpe.

The records of the region's former water boards are also kept by the Regionaal Archief. Moreover, in order to supplement the official records, the Regionaal Archief also preserves those of private organizations and individuals that are of interest as cultural heritage.

The Regionaal Archief keeps more than records. It has an extensive library and a historical topographic atlas with a large collection of visual material. It is possible to view the library catalogue and part of the visual material on the website of the Regionaal Archief.