Clitandre and Acaste discuss their affections for Célimène. When Clitandre asks why Acaste is always so cheerful, Acaste arrogantly notes that he is young, rich, and attractive, and therefore has no reason not to be cheerful. Acaste's disposition changes when he admits that his love for Célimène goes unrequited. He and Clitandre agree that, should one of them fall out of favor with Célimène, he will stop courting her, yielding to the other.
Célimène discovers that Clitandre and Acaste are still in the house. Clitandre claims, "It's love that detains us."
Basque announces the arrival of Arsinoé, a woman whose company neither Célimène nor Acaste can bear. Célimène mentions that Arsinoé has feelings for Alceste, thus making Arsinoé jealous of Célimène.
Arsinoé informs Célimène that people have been speaking critically of her "flirtatiousness." While Arsinoé claims to have spoken in defense of Célimène, Arsinoé comes across as insincere, and her jealousy of Célimène is apparent. Arsinoé recommends that Célimène change her ways.
Célimène responds to the attack on her character by criticizing Arsinoé's "excessive piety" and pretentiousness, suggesting that Arsinoé is a hypocrite. Célimène adds that people have been discussing Arsinoé's faults as well. Célimène allows that it may just be Arsinoé's age that causes her to behave as she does. Arsinoé rebuffs, arguing that Célimène should be careful not to place too much value on her youth. Arsinoé claims that Célimène's courtiers are attracted to her lack of restraint, not her "good qualities."
Alceste enters as Célimène leaves, and Alceste and Arsinoé are left alone together. Arsinoé praises Alceste's integrity, expressing her disapproval of the way the Court has handled Alceste's legal matters. Alceste rejects Arsinoé's compliments, contending that she should be more discriminating in her flattery. Arsinoé continues, however, mentioning that she could "pull a few strings" to get Alceste a "post at Court." Alceste rejects her offer. In a last-ditch attempt to gain Alceste's affection, Arsinoé tells him that Célimène has been deceiving him. Arsinoé claims that she has proof of Célimène's deception at her house.