The history of the Nationalgalerie begins with an act of patronage. When the banker and consul Joachim Heinrich Wilhelm Wagener bequeathed his painting collection to the king of Prussia upon his death on 18 January 1861, he explicitly linked the gift with his desire for the establishment of a “national gallery”. Wilhelm I’s acceptance of the donation is now viewed as the founding act of the Nationalgalerie. The “National Gallerie Inventarium A” that was created at that time begins with the handwritten comment: “For the paintings in the Wagner Collection, the old (Waagen) catalogue of the same provides the inventory register”. This was a reference to the register of the Wagener Collection made by Gustav Friedrich Waagen, Director of the Gemäldegalerie, which bore the code WS.

The A Inventory is strictly limited to works of painting, with the first entry dated 22 March 1861. The B Inventory for sculpture was begun on 10 June 1865. The successive inventory logs are numbered with Roman numerals. This practice continued at the Nationalgalerie on the Museumsinsel during the existence of the GDR, which led to the creation of the inventories A I–IV and B I–III. However, there is one particularity contained in the inventory logs A III and B II: they initially served as a central registry of the artworks that were acquired by the oberpräsidents and the regierungspräsidents of the Prussian government for their own use. They also included the artworks that  the Prussian minister for science, art and education acquired, which, though inventoried in the Nationalgalerie, were assigned for use by other institutions. Since these kinds of entries were discontinued in 1930, the two volumes were later also used for cataloguing works that belonged to the Nationalgalerie.

After the division of Germany, an independent inventory log was established in West Berlin. While in the A and B Inventories the works were assigned consecutive object numbers within the individual volumes, in the new NG inventory, the numbers start again every year (1/50–9/50; 1/51–16/51; and so on). What’s more, the objects are no longer divided according to medium, meaning that all acquisitions have been recorded in the same inventory logs. This approach for cataloguing all the Nationalgalerie’s acquisitions has continued since the reunification of the Nationalgalerie in 1992.

The artworks belonging to the state of Berlin that were incorporated into the collection of the Nationalgalerie (such as the collection of the former Galerie des 20. Jahrhunderts) are listed in an inventory maintained by the Berlin Senate, where the works are ascribed the letter B (for Berlin), but are not followed by a Roman numeral. There is also a separate inventory for artworks belonging to the association Freunde der Nationalgalerie (FNG), which was founded in 1977, and the FNG’s foundation (the SFNG), set up in 2005. There are three appendices to the five NG inventory logs, listing the acquisitions and donations from the Berggruen, Marzona, and Flick Collections. Works that the Nationalgalerie holds as long-term loans are recorded in the inventory as “externally owned assets” (fremdvermögen – F.V.).

There are also a number of historical inventories belonging to now-defunct collections, such as those of the Rauchmuseum (abbreviation RM) and the Beuth-Schinkel-Museum (B.S.M.), the Modell- und Abgusssammlung (G for gips, or plaster), and the Skulturensammlung West (SKS). The Sammlung der Zeichnungen (F I–IV) is now held by the Kupferstichkabinett.