In Book One of Sofia's Ellis Island Diary, renowned author Kathryn Lasky tells the story of Sofia Monari's arrival in America from Italy. When Sofia and her family arrive in Ellis Island after a long and difficult journey from Italy, a cruel twist of fate separates Sofia from her parents and sends her into "quarantine." There, in a state-run hopsital, she and her new friend, Maureen, must learn to overcome the twin hardships of immigration and alienation, while they maintain the hope that they will be reunited with their families.

Kathryn Lasky brings readers the second installment of Sofia's Ellis Island Diary, depicting Sofia's move to the North End of Boston and her first steps as a new American. After her dramatic release from quarantine and reunion with her family, Sofia moves to the North End of Boston, where the Monaris start their new lives in their new country. While her parents struggle to make ends meet, Sofia must adjust to her American school, friends and job.

In her third and final diary, by Kathryn Lasky, Sofia continues to face the hardship of her new life in America with her cheerful and courageous spirit. Sofia continues to chronicle life in her new home, the North End of Boston, as her best friend Maureen comes to live with her, and her parents open their own store. Sofia describes the daily hardships and joys that she meets as a new American.