Mother Courage opens in Dalarna, in spring of 1624. A Sergeant and Recruiting Officer are recruiting soldiers for the Swedish campaign in Poland. They stand shivering on a highway outside a town. The Officer complains of the difficulty in recruiting soldiers from the untrustworthy townspeople. The Sergeant declares that the people could use a good war. Without war, there is no organization.

A harmonica is heard, and a canteen wagon appears on stage. The infamous Mother Courage sits on it with her dumb daughter, Kattrin, and her sons, Eilif and Swiss Cheese pull it along. Introducing herself to the officers, she sings her trademark song. A "sales pitch" of sorts, it markets the wares that will help the soldiers march to their deaths. She calls the soldiers to wake: "Let all of you who still survive/ Get out of bed and look alive!"

The Sergeant demands to see her license. Fishing out a number of papers, Courage mocks his request. He again bemoans the lack of discipline in the army and asks the group's names. Courage reveals her family's rather colorful lineage, each of her children being the offspring of a different, and perhaps forgotten, father of a different nationality. The two officers deride her, and Eilif threatens to punch them out. Courage silences him and offers the men her wares.

The Recruiting Officer reveals his intentions and attempts to seduce Eilif into the army. Courage demands that he leave her children alone, ultimately drawing her knife. The Sergeant protests, saying that since Courage lives off the war, the war should not ask something of her in return. The war has not done him any harm. Looking into the future, Courage disagrees. To her, the Sergeant is a corpse on furlough.

To confirm her prophecy, she has the Sergeant choose his fortune. Courage puts two strips of parchment in his helmet, drawing a black cross on one of them. She mixes them, and he draws. To his horror, the Sergeant has chosen his death.

Unbeknown to Courage, the Recruiting Officer has continued his pursuit of Eilif. When Eilif admits that he would like to sign up, Courage similarly foretells the fate of her children. Each draw the black cross as well. She laments their fate. Eilif will die for his excessive bravery, Swiss Cheese for his honesty, and Kattrin for her kindness. Sorrowfully, she readies to leave.