It is Mrs. Higgins' at-home day, and she is greatly displeased when Henry Higgins shows up suddenly, for she knows from experience that he is too eccentric to be presentable in front of the sort of respectable company she is expecting. He explains to her that he wants to bring the experiment subject on whom he has been working for some months to her at-home, and explains the bet that he has made with Pickering. Mrs. Higgins is not pleased about this unsolicited visit from a common flower girl, but she has no time to oppose before Mrs. and Miss Eynsford Hill (the mother and daughter from the first scene) are shown into the parlor by the parlor-maid. Colonel Pickering enters soon after, followed by Freddy Eynsford Hill, the hapless son from Covent Garden.
Higgins is about to really offend the company with a theory that they are all savages who know nothing about being civilized when Eliza is announced. She makes quite an impact on everyone with her studied grace and pedantic speech. Everything promises to go well until Mrs. Eynsford Hill brings up the subject of influenza, which causes Eliza to launch into the topic of her aunt, who supposedly died of influenza. In her excitement, her old accent, along with shocking facts such as her father's alcoholism, slip out. Freddy thinks that she is merely affecting "the new small talk," and is dazzled by how well she does it. He is obviously infatuated with her. When Eliza gets up to leave, he offers to walk her but she exclaims, "Walk! Not bloody likely. I am going in a taxi." The Mrs. Eynsford Hill leave immediately after. Clara, Miss Eynsford Hill, is taken with Eliza, and tries to imitate her speech.
After the guests leave, Mrs. Higgins chides Higgins. She says there is no way Eliza will become presentable as long as she lives with the constantly-swearing Higgins. She demands to know the precise conditions under which Eliza is living with the two old bachelors. She is prompted to say, "You certainly are a pretty pair of babies, playing with your live doll," which is only the first of a series of such criticisms she makes of Higgins and Pickering. They assail her simultaneously with accounts of Eliza's improvement until she must quiet them. She tries to explain to them that there will be a problem of what to do with Eliza once everything is over, but the two men pay no heed. They take their leave, and Mrs. Higgins is left exasperated by the "infinite stupidity" of "men! men!! men!!!"
In this, Eliza's first debut and debacle, we are shown that just speaking correctly is not enough to pass a flower girl off as a duchess. As Higgins knows, "You see, I've got her pronunciation all right; but you have to consider not only how a girl pronounces, but what she pronounces." Mrs. Higgins puts it succinctly with the line, "She's a triumph of your art and of her dressmaker's; but if you suppose for a moment that she doesn't give herself away in every sentence she utters, you must be perfectly cracked about her." In other words, there are aspects to a person that are susceptible to change or improvement, but these cannot override those aspects that are innate to that person, which will surface despite the best grooming.
While it may seem that this is the act in which Eliza is exposed for what she is, just about all the other characters are shown up in the process. Pickering and Higgins are an example. After they have been shown to be the undoubted masters of their (phonetic) dominion, lording it over Eliza, here, in Mrs. Higgins' feminine environment, they come across more like over-enthusiastic, ineffective little boys than mature men of science. Mrs. Higgins repeatedly rebukes Higgins for his lack of manners, his surly behavior towards her guests, and for his klutzy habit of stumbling into furniture, and is very reluctant to have him in front of company. This act also reveals middle class civility for what it really is--something dull and uninspiring. Mrs. Higgins' at-home turns out to be an unexciting conversation determinedly choked full with "how do you do's" and "goodbye's," with barely anything interesting said in between. In fact, the only time something is said with any spirit is when Eliza forgets herself and slips back into her normal manner of speaking. Clara Eynsford Hill, for example, is shown to be a useless wannabe with no character of her own (quite in contrast to the feisty and opinionated Eliza). So unremarkable is the mother-son-daughter threesome of the Eynsford Hills that Higgins cannot recall where he has met them (at Covent Garden, in the first act) until halfway through this act. He can only tell that their voices are familiar, suggesting that all they have to recommend them is their accents, and nothing else. If staged well, this act can expose the clumsiness and vapidity of polite Victorian society, causing us to question if the making of a duchess out of a flower girl is really doing her a favor.
We get another indication in this act that Higgins is incapable of being the romantic hero of the play. We see that when he says to this mother, "My idea of a lovable woman is somebody as like you as possible. I shall never get into the way of seriously liking young women: some habits lie too deep to be changed." The irony is that even though he has no doubt that he can transform Eliza, he takes it as a given that there are natural traits in himself that cannot be changed.