Exciting new things come to the Larsons' farm in Minnesota in the springtime - including a big new barn and a tiny new baby. But changes bring new worries and more work for Kirsten, too. First she is afraid for Mama's health. Then caring for a baby keeps her so busy that her life seems to be nothing but chores. Soon Kirsten doesn't even have time to help with the surprise she and her friends are planning for their teacher, Miss Winston. And when she has to miss school to help out at home, she worries that her friends will forget her. But Kirsten's hard work is rewarded, and her tenth birthday becomes a celebration of family and friendship.