In Pollyanna Grows Up we follow the titular character as she “grows up” through a story told in two connected parts. The first part takes place in Boston when she is age 13, having just been rehabilitated from severe injuries sustained in an automobile accident. As she leaves the hospital, she is sent to stay with a nearby dowager, who has long withdrawn into grief, pining for her lost nephew. Pollyanna is to be her “cure.” After leaving Boston, Pollyanna leaves the country with her Aunt Polly and doesn’t return to Vermont until she is 20 years old.

While in Boston, Pollyanna observes her host’s isolation and depression, which sits in stark contrast with the opulence of her home and her material wealth. Meanwhile, naive, relentlessly positive, literal-minded Pollyanna, often oblivious to the structure of society around her, slowly comes to understand the dire, grinding poverty, isolation, and alienation that turn-of-the-century Boston was also home to. Human connection is a central theme of the book and Pollyanna begins to engage with broader cultural and moral questions of her society before departing the country.

In the second half of the book, Pollyanna acts as host to the friends she made in Boston. As such, she reconnects with them and puts them in touch with her friends and family in Vermont. As a part of growing up, Pollyanna must now address questions of how these relationships might change as her age and social status change. She must reconcile the sense of obligation she feels with her desires, and with the wants and needs of those around her. Old relationships are expanded, and new relationships are formed (or revealed) with each, in the end, more connected to all.