The institution now called the Norton Simon Museum was founded in 1924 as the Pasadena Art Institute, later reorganized as the Pasadena Art Museum. By the early 1970s, the museum had built a significant reputation for contemporary art — particularly for its presentations of work by Picasso, Cézanne, and other modernists — and had constructed a new building on Colorado Boulevard designed by architect Ladd & Kelsey. But the new building had been expensive, the operating costs were unsustainable, and the museum was effectively insolvent.

Norton Simon was an industrialist — he had built a business empire that included Hunt Foods, McCall Corporation, Canada Dry, and other companies — who had been collecting art seriously since the 1950s. He had also been buying into the Pasadena museum's governance. In 1974, he took over the institution formally, renamed it, and installed his own collection as its permanent core. The Pasadena Art Museum's contemporary focus gave way to Simon's preferences: old masters, Impressionism, Post-Impressionism, and Asian sculpture.

Norton Simon had bought, by the time he redirected the Pasadena museum, one of the most significant private art collections in the United States. The European holdings run from medieval paintings through the twentieth century, with particular depth in the Dutch and Flemish baroque — Rembrandt, Rubens, Frans Hals — and in Impressionist and Post-Impressionist work. Degas is represented by one of the most extensive holdings of his work anywhere, including bronzes, pastels, and paintings that trace his obsession with dancers and bathers across decades.

The Asian collection is less expected and equally serious. Simon began buying Indian and Southeast Asian sculpture in the 1970s, partly in response to a legal and ethical controversy: a Shiva Nataraja he had purchased was identified as a stolen object, and the process of returning it to India prompted Simon to engage more deeply with the field. The Asian galleries now include Chola bronzes, Cambodian sculpture from the Angkor period, and works from across the subcontinent spanning more than two millennia.

The 1,000-pound Rodin sculpture of The Thinker near the museum's entrance is among the most frequently photographed objects in Pasadena. The full garden, designed by landscape architect Nancy Goslee Power and containing a reflecting pool, is planted with trees and ground cover that changes with the seasons.

The Norton Simon Museum sits at the western end of Colorado Boulevard, the street that the Rose Parade has traveled since 1890. On New Year's Day, television cameras positioned along Colorado Boulevard broadcast the parade to a worldwide audience, and the museum's distinctive low building is visible in the background of shots taken at this end of the route. The museum is effectively part of the visual vocabulary of one of the most-watched annual American events, whether or not the viewers at home know what they are looking at.

The museum is managed under an agreement between the Norton Simon Art Foundation and the City of Pasadena. Norton Simon died in 1993; his wife, actress Jennifer Jones, had been instrumental in the museum's operation and continued in that role until her own death in 2009. The collection continues to grow through acquisition. The building, originally designed for a different institution with different purposes, has been adapted successfully to Simon's collection — the Degas room, in particular, organized to show the sculptures and pastels in relationship to each other, feels purpose-built for the works it holds.