The Deltaplan of the Netherlands provided the impetus for the reorganization of the collection belonging to the Zuiderzee Museum. The historical background and development of the collection is described. The collection is broad in scope and consists of fine art, costumes, jewellery, ships, historic buildings and their contents. In 1989 a management review revealed that the storage spread over thirty locations was uncontrolled and not secured. As well, the lack of an acquisitions policy resulted in a huge collection with very few administrative records and descriptions. With the Deltaplan in place, a new acquisitions procedure was created to curb growth of the collection and to raise awareness of administrative concerns including registration, storage and preservation. The objects were categorized as belonging to the core, requisite or disposable collections. Disposable items included objects outside of regional collection areas, objects considered beyond repair and duplications. The vetted collection has been reduced to 40, 000 high quality items from over 100,000 pieces.