[7] The gallery became of the hub of social activity in Sacramento, hosting benefits for local organizations and welcoming prominent visitors including the Hawaiian queen, Liliʻuokalani (1878), President Ulysses S. Grant (1879), and Oscar Wilde (1882).

In 2002, to accommodate a burgeoning collection and the needs of the growing population of Sacramento and California's Central Valley region, the museum commissioned the firm of Gwathmey Siegel & Associates to design a major addition.

[10] The Californian collection continued to expand, and now contains 150 years of painting, sculpture, and craft media covering genres that include Impressionism, Abstract Expressionism, and Pop Art, and features artists including early Sacramento painter Amanda Austin, Norton Bush, William Keith, Thomas Hill, Granville Redmond, Edwin Deakin, Guy Rose, Gottardo Piazzoni, Joan Brown, Elmer Bischoff, Roland Petersen, David Park, Jess, Richard Diebenkorn, Mel Ramos, and Wayne Thiebaud.

American impressionists and modernists are a particular strength, with artists including Childe Hassam, Robert Henri, Georgia O'Keeffe, Maynard Dixon, Marsden Hartley, Hans Hofmann, and Luis Cruz Azaceta.

[11] As a later director of the museum would write, "Mr. Crocker was a novice and completely susceptible to a kind of fraud in his anxiety to become the possessor of a large collection of masterpieces.

"[12] (Works said to be by Rembrandt, Rubens, Poussin, Salvator Rosa, and even Leonardo da Vinci appear in the initial 1876 catalogue, but were reattributed in following decades.

[11] Of more certain provenance were the numerous German and Central European paintings Crocker purchased, many by artists who were alive and working at the time.

These 19th-century paintings would form the core of the European collection, along with a number of 17th-century Flemish and Dutch Golden Age still lifes and genre scenes, as well as French and Italian works of the 17th and 18th centuries.

[18] Artists represented in Crocker's original collection include Maarten van Heemskerck, Jan Brueghel the Elder, Klaes Molenaer, Pieter Quast, Antonio Joli, Francesco Solimena, Paolo de Matteis, Claude-Joseph Vernet, Jacques-Louis David, Andreas Achenbach, Maria van Oosterwyck, and Karl von Piloty.

These include three small bronzes, two terra cotta relief sculptures, a Cagnes landscape painting, and works on paper,[22] and also a ceramic vase by Jean Renoir.

The collection of Asian art is noted for its holdings of Chinese tomb furnishings and trade ceramics, and Japanese armor and tea ware.

The history of ceramics is also explored through a collection of 18th-century Meissen porcelain tableware and in the works of ancient cultures dating to the Neolithic period.

The collection of African and Oceanic art features a variety of objects created for daily life and traditional ceremonies.

Artists whose works have appeared include Robert Arneson, Elmer Bischoff, David Gilhooly, Ralph Goings, Roland Petersen, Mel Ramos, Fritz Scholder, and Wayne Thiebaud.

Crocker asked Babson to design an elaborate gallery building in the Italianate style[26] that would sit adjacent to the mansion and display the family's growing art collection.