Earlier archive edits
The first editing of the Cuypers archive was initiated by the Amsterdam professors C. Peeters and C.A. van Swigchem. For this purpose, the archive was transferred to the library and documentation center of the Catholic University (KDC) in Nijmegen in 1969. The archive to be processed consisted of two parts. Part A (see above) came from the RDMZ and consisted of 15 crates with bundles of drawings, 13 large and medium-sized portfolios and various plate works. Part B (see above) came from the Cuypers depot at the Rijksmuseum and was stored in 25 laundry baskets, 8 large portfolios, 20 large sliding members and also contained loose material. In addition to items from the Rijksmuseum file described in this inventory, this part included the archives of the architects K.P.C. de Bazel and J.J., M.A. and J. van Nieukerken.
Both parts of the archives (A and B) were edited by students F. Asselbergs and H. van Crimpen from 1969 to 1971. The first access, consisting of fiche cards, dates from that time. The cards were made at the time with the intention of providing a standard description of all projects present in the archive. The following information was noted on the fiche cards: location, type of building, type of assignment, client, date and architect. Then it was checked which projects were found to have drawings, correspondence and documentation. Then the numbers of the packages were also noted on the cards. These numbers have since functioned as application numbers. The maps were organized in various ways: by topography, by building type, by year and by folder number. Drawings by other architects were also described in a separate catalog. The card bins could thus be used as access to the archive until 1991.
However, the archival editing by Asselbergs and Van Crimpen was never fully completed. Not all of the material was described on the fiche cards and non-project-related material was not described at all. After editing, the archive moved from Nijmegen to Amsterdam in 1971, where it was managed by the NDB. A part containing mainly person-related material remained with Asselbergs for study and was added to the rest of the archive in 1992 and described globally as a supplement.
When the NAI was established in 1988, the archive was prepared for its move to Rotterdam. To this end, the various parts of the archive were given codes: CUYP, CUYX and CUCO.
The archive of P.J.H. (Pierre) Cuypers with code CUYP concerned the bureau archives of Roermond and Amsterdam with a size of about 250 linear meters. In 1993, the fiche cards arranged by topography in the card index were used as the basis for an inventory. This topographical access consisted of six ring binders:
Part I: Correspondence and photographic plates;
Part II a + b: Drafts (drawings); Supplements (miscellaneous; particularly unordered part of the archive);
Part III: Negatives;
Appendix I: Further accesses to the Rijksmuseum file in Amsterdam;
Appendix II: Further accesses to the file of De Haar Castle in Haarzuilens; Indexes: Indices by toponym and keyword on the copybooks (both general and those of the Rijksmuseum); List of chiefs of the art workshop; Inventory of Cuypers' bookstore.
The archive of J.Th.J. (Joseph) Cuypers with code CUYX, dated from 1880 to 1958 and measuring approximately 12 linear meters, covered only a portion of the entire archive formed by Joseph. The vast majority of his archives were in CUYP because of the collaboration with his father. CUYX also contained the archives of P.J.J.M. Cuypers, Joseph Cuypers' son.
The archive of art workshop Cuypers, Stoltzenberg and Co. with code CUCO, included about 150 linear meters and was dated from 1852 to 1907.
In 1992, the temporary collection of archival negatives and slides with code CAND was formed at the NAI. This housed 293 glass negatives originating from CUYX and 564 glass negatives originating from CUCO.

Archive processing 2003
The Cuypers archive was accessible and consultable. In practice, however, consultation proved difficult for (scientific) researchers, (restoration) architects, exhibition designers and the interested NAI reading room visitor. Factors that made consulting the archives difficult were: the size of the (sub)archives and files; the accesses were imprecise, incomplete and often incorrect; material documenting one project was in different sub-collections; the non-project-related material was not described, nor were the post-1973 acquisitions; the original serial character of the drawings and written documents was no longer intact; material by other architects had entered the archive in the past; the material condition of large parts of the archive was poor, consultation and availability were therefore in many cases actually irresponsible.
It was expected that the demand for a clear and responsible inventory would increase in the near future. This was prompted in part by the remodeling and restoration of two of Cuypers' largest projects: the Rijksmuseum in Amsterdam and De Haar Castle in Haarzuilens, and the related scientific and architectural investigations. There was also hope that a proper inventory on the colossal archive might contribute to a monograph that was still missing. The significance of nineteenth-century architecture had been emphasized in previous publications. Study of the source material could enhance the quality of the debate about it.
In view of the state of the archives, the quality of the entries and the need for a good inventory, it was decided in 2000 to start working on the Cuypers archive again. It began with the inventories of the building file of De Haar Castle (code HAAR) and that of the Rijksmuseum (code RYKS). These two inventories were completed in 2001 and 2002, respectively. The Rijksdienst voor de Monumentenzorg largely financed the first inventory. Funding for the inventory and conservation/restoration of the Rijksmuseum file was provided by the National Building Service.
In 2002, the Getty Grant Program of the Getty Center of Los Angeles awarded a grant to the NAI for the inventory of the remaining Cuypers archive. This editing began in 2003. First, the Central Station file - Cuypers' third major project (code CENT) - was taken up. After that, work began on the Cuypers Bureau Archive (code CUBA) and the archive of the Cuypers Workshop (code CUCO). Finally, the personal documents were inventoried (code CUYP), including the extensive photo archive. At the end of 2007, the entire project could be completed.

Addition 2002
In 2002, the contents of a "last forgotten cupboard" were transferred from the castle to the NAI. This consisted solely of written documents, particularly correspondence and financial records. Since the inventory had already been completed, the descriptions of these archival items were added to the existing inventory. The 2002 acquisition can be recognized by the higher request numbers (from HAARd150).