Norma, dagger in hand, tries to bring herself to murder her children in their sleep to protect them from living disgracefully without a father (“Teneri, teneri figli”). She changes her mind and summons Adalgisa, advising her to marry Pollione and take the children to Rome. Adalgisa refuses: she will go to Pollione, but only to persuade him to return to Norma. Overcome by emotion, Norma embraces her, and the women reaffirm their friendship (Duet: “Mira, o Norma”).
The Druids assemble at their altar to hear Oroveso’s announcement that a new commander will replace Pollione. Oroveso rages against the Roman oppression, but tells the Druids that they must be patient to ensure the success of the eventual revolt (“Ah! del Tebro al giogo indegno”).
Norma is stunned to hear from Clotilde that Adalgisa’s pleas have not persuaded Pollione, and in a rage she urges her people to attack the conquerors. Oroveso demands a sacrificial victim, and just then Pollione is brought in, having profaned the sanctuary. Alone with him, Norma promises him his freedom if he will leave Adalgisa and return to her (Duet: “In mia man alfin tu sei”). When he refuses, Norma threatens to kill him and their children, and to punish Adalgisa. She calls in the Druids and tells them that a guilty priestess must die, then confesses that she is referring to herself. Moved by her nobility, Pollione asks to share her fate. Norma begs Oroveso to watch over her children, then leads her lover to the pyre.