Stein's writing can be placed in three categories: "hermetic" works best illustrated by The Making of Americans: The Hersland Family; popularized writing such as The Autobiography of Alice B. Toklas; and speech writing and more accessible autobiographical writing of later years, of which Brewsie and Willie is a good example. Her works include novels, plays, stories, libretti and poems written in a highly idiosyncratic, playful, repetitive, and humorous style. Typical quotes are: "Rose is a rose is a rose is a rose"; "Out of kindness comes redness and out of rudeness comes rapid same question, out of an eye comes research, out of selection comes painful cattle"; about her childhood home in Oakland, "There is no there there"; and "The change of color is likely and a difference a very little difference is prepared. Sugar is not a vegetable."
These stream-of-consciousness experiments, rhythmical essays or "portraits", were designed to evoke "the excitingness of pure being" and can be seen as literature's answer to Cubism, plasticity, and collage. Many of the experimental works such as Tender Buttons have since been interpreted by critics as a feminist reworking of patriarchal language. These works were well received by avant-garde critics but did not initially achieve mainstream success. Despite Stein's work on automatic writing with William James, she did not see her work as automatic, but as an 'excess of consciousness'.
Though Gertrude collected cubist paintings, especially those of Picasso, the largest visual influence on her work is that of Cézanne. Particularly, he influenced her idea of equality, distinguished from universality: "the whole field of the canvas is important" (p. 8). Rather than a figure/ground relationship, "Stein in her work with words used the entire text as a field in which every element mattered as much as any other." It is a subjective relationship that includes multiple viewpoints. Stein explained: "The important thing is that you must have deep down as the deepest thing in you a sense of equality."
Her use of repetition is ascribed to her search for descriptions of the "bottom nature" of her characters, such as in The Making of Americans where the narrator is described through the repetition of narrative phrases such as "As I was saying" and "There will be now a history of her." Stein used many Anglo-Saxon words and avoided words with "too much association". Social judgement is absent in her writing, so the reader is given the power to decide how to think and feel about the writing. Anxiety, fear and anger are also absent, and her work is harmonic and integrative.
Stein predominantly used the present progressive tense, creating a continuous present in her work, which Grahn argues is a consequence of the previous principles, especially commonality and centeredness. Grahn describes "play" as the granting of autonomy and agency to the readers or audience: "rather than the emotional manipulation that is a characteristic of linear writing, Stein uses play." In addition Stein's work is funny, and multilayered, allowing a variety of interpretations and engagements. Lastly Grahn argues that one must "insterstand... engage with the work, to mix with it in an active engagement, rather than 'figuring it out.' Figure it in."
In 1932, using an accessible style to appeal to a wider audience, she wrote The Autobiography of Alice B. Toklas; the book would become her first best-seller. Despite the title, it was actually Stein's autobiography. The style was quite similar to that of The Alice B. Toklas Cookbook, which was written by Toklas.
Several of Stein's writings have been set to music by composers, including Virgil Thomson's operas Four Saints in Three Acts and The Mother of Us All, and James Tenney's setting of Rose is a rose is a rose is a rose as a canon dedicated to Philip Corner, beginning with "a" on an upbeat and continuing so that each repetition shuffles the words, e.g. "a/rose is a rose/is a rose is/a rose is a/rose."