Berkeley No. 1 is the first in a series of more than fifty abstractions painted by Diebenkorn between 1953 and 1955, shortly after his return to Berkeley, California. At this early point in his career, Diebenkorn, who had been painting abstractions since the mid 1940s, held to the goal of expressive color, non-objectivity, and flatness in his art. While his interest in defining images by color rather than line initially stemmed from his lifelong admiration of works by Cézanne and Matisse, his purely abstract, non-representational mode reflected the influence of the New York abstract expressionists, many of whom he had met when he visited New York in 1946-47 and 1953. In addition, the atmosphere at San Francisco's California School of Fine Arts during the late 1940s was dominated by the presence of Clyfford Still, who also had brought the ideas of Gorky, Rothko, and Pollock from New York. By the early 1950s, Diebenkorn's style incorporated the color expanses of Motherwell, Rothko, and Still, combined with the flesh tones and punctuated, forceful lines of de Kooning. This approach is exemplified by the Berkeley paintings, such as Berkeley No. 1, which were seen as a West Coast form of abstract expressionism.
Berkeley No. 1 is a two-dimensional abstraction composed of broad expanses of gestural color highlighted with sketchy, broken tendrils of black paint. At first glance, the composition of spattered and ripped paint appears to have been effortlessly created; however, upon closer examination one can see that Diebenkorn built up the surface in several layers. The paint texture of Berkeley No. 1 varies widely from heavy impasto to thin wash, also typical of the artist’s way of painting.
Although Diebenkorn's later Berkeley paintings are his most gestural and active, they stop short of the explosive effect for which abstract-expressionist painting is known. The reserved air of Berkeley No. 1 is maintained by the tendency of the color areas to remain within discrete boundaries, despite the highly visible, frenetic, and multi-directional brushstrokes. The composition is divided into three distinct tiers of color—a central band of tans, pinks, ochres, and purple sandwiched between strips of predominantly white—adding to the controlled nature of the image. The Berkeley series was the closest Diebenkorn came to the abstract-expressionist style, but Diebenkorn arrived at his own working method through the manipulation and placement of passages of pure color.
Diebenkorn's Berkeley works grew out of his earlier landscape series, which have been compared to aerial views on the basis of their horizontal orientation, their color and light, and their abstraction. Diebenkorn adopted colors that mirrored the mood of the environments in which he worked; the Berkeley series is characterized by intense, clear color—a reflection of the sunny, temperate California climate.