More than two months pass. Winter arrives, and Katy’s room has been transformed—bright, orderly, and filled with flowers. Though she still has difficult days, she is progressing steadily, sustained by frequent gifts and notes from Cousin Helen.

As Christmas approaches, Katy proposes that the children hang their stockings in her room. Aunt Izzie unexpectedly gives her five dollars, which Katy uses to buy everyone gifts: a writing desk for Elsie, a sled for Johnnie, books for Dorry and Cecy, and small items for the servants. She also secretly arranges with her father to buy a book for Aunt Izzie.

On Christmas Eve, the children hang their stockings and write wishes on paper to throw into the fire—if the papers fly up the chimney, the wish will be granted; if they simply burn, it is lost. Elsie’s wish burns up, disappointing her, but Clover cleverly creates a draft that sends hers up the chimney. After the children leave, Katy notices no one has hung a stocking for her. She feels hurt but says nothing. On Christmas morning, all the children’s wishes are granted, and they surprise Katy with a decorated miniature tree hung with treats and small gifts. The tree stands on a new reclining chair from Dr. Carr that allows Katy to be moved to the window, with a silver bell from Cousin Helen and a book from Cecy tied to its arms.

Several weeks later, Katy begins using the chair regularly. Sitting by the window and seeing the outside world after six months in bed brings her joy.

When Katy and Cecy wish another saint would visit them, they settle on Saint Valentine and plan a surprise party. The children receive invitations to tea in Katy’s room, now dubbed “Queen Katherine’s Palace.” After a pleasant meal, mysterious letters arrive with personalized valentines for each child—a clover-shaped pincushion and poem for Clover, an ivory seal for Elsie, a humorous poem for Dorry, a paper doll for Johnnie, a piece of rubber for Phil, and romantic verses for Cecy. Katy reads her own simple valentine, which she wrote herself to avoid seeming left out. Dorry remarks that they never had such good times before Katy was sick—a comment that gives her mixed feelings of pleasure and sorrow.

After everyone leaves, Katy reads a letter from Cousin Helen containing a poem about learning in the “School of Pain” under two teachers, Love and Pain, who sometimes seem alike.

The following summer brings stifling heat that Katy, unable to move to cooler spots, must endure. Though she grows pale and weak, she maintains her patience. Dr. Carr tries taking her for drives, but the movement causes too much pain. When cool September weather arrives, Katy revives and asks to take French lessons from Mr. Berger.

This second winter is harder than the first. One day, Clover reports that Aunt Izzie has an unusual headache. Over the following days her illness grows worse, and Dr. Carr reveals she has typhoid fever. The younger children are sent to stay with Mrs. Hall. The house becomes somber and hushed until one morning Katy wakes to find that Aunt Izzie has died during the night. The girls sob together, consumed with regret for all the times they troubled their aunt and failed to appreciate her.

After the funeral, Katy begs her father to let her manage the household from her chair rather than hire a housekeeper. She argues that the experienced servants need only occasional direction and that Clover can watch for problems. Though doubtful, Dr. Carr agrees to a month’s trial.

Katy finds the work manageable thanks to Aunt Izzie’s well-established routines. Her first challenge is planning menus—she becomes absorbed in recipe books and puts the family through many strange meals before returning to simpler fare. A phase of strict attention to healthful eating follows until Dr. Carr intervenes. Later she becomes overanxious about household details, constantly sending Clover to check on the bread or insisting the children wear overshoes. Despite these missteps, Katy improves steadily, and Dr. Carr observes her growing cheerfulness and competence with satisfaction.

Two years have passed. Clover, now over 14, sits sewing on the front steps, noticeably more mature. Phil, now a big boy in trousers, comes to ask Katy if currants are ripe enough to eat—a sign of the caution Dr. Carr instilled after once punishing the children with salts for eating green gooseberries.

Upstairs, Katy appears in a wheeled chair that allows her to move independently around her room. Dorry, now a tall, mechanically inclined youth, brings her clock, which he claims to have repaired. When it begins striking, it continues well past 11 o’clock before stopping. Though mortified, Dorry asks to try again, and Katy kindly agrees, suggesting he consult the shop. Johnnie rushes in to report that Phil is washing baby chicks in the rain barrel, believing their yellow down is egg residue. Katy summons Phil and gently explains the harm; touched by her kindness, he agrees to warm them.

Imogen Clark makes an unannounced visit, announcing her family’s return to Jacksonville and reading from a letter from her supposed beau, the Brigand. Katy and Clover stifle giggles. Then, Mrs. Worrett, a stout old friend of Aunt Izzie’s, arrives unexpectedly from the country. Though the house is in disorder with no proper dinner prepared, Katy receives her graciously and instructs Bridget to serve an improvised lunch and tea. Despite finding Mrs. Worrett tiresome, Katy and the girls entertain her courteously for hours. As she departs, Mrs. Worrett praises Katy’s hospitality, saying Aunt Izzie would be pleased. That evening, when the children want to laugh about the visit, Katy defends the woman, saying it honors Aunt Izzie’s memory to show kindness to her friends. Cecy whispers to Clover about how sweet Katy has become, and Clover agrees—adding that she almost dreads Katy getting well, though she knows the thought is selfish.

Six weeks later, Katy urgently rings her bell to summon Clover and Elsie: She has just stood up by herself for the first time, holding the chair arm throughout. The next day she stands again with Clover present, and the household rushes to witness it. Dr. Carr is overjoyed but cautions her to progress slowly, warning that any imprudence could cause a setback.

Katy’s recovery proceeds gradually. She learns to stand for increasing periods, then without support, then to walk while pushing a chair. Soon she ventures to other rooms on the second floor. When she wishes to attempt the stairs in late August, her father advises waiting.

Clover proposes a celebration for Katy’s first descent. Katy chooses September 8, her mother’s birthday. For the next 10 days, mysterious preparations occur downstairs while Clover keeps Katy’s door shut. On the appointed morning, everyone dresses in their finest. Dr. Carr and Dorry slowly escort Katy downstairs while the household watches.

When Dr. Carr opens the parlor door, Katy sees the room has been refreshed, a new sun-facing window installed, and a couch and table arranged near it. Most astonishingly, Cousin Helen lies waiting on the sofa—Clover’s secret plan. Forgetting her weakness, Katy runs to embrace her. Cousin Helen will stay three weeks.

During her visit, Cousin Helen observes how much the children have improved and how they all revolve around Katy. She watches Katy handle Phil’s tears, Johnnie’s confidences, and Elsie’s requests with consistent gentleness and wisdom, and tells Katy she has successfully learned her lessons and become the heart of the family. Katy protests tearfully that she has often been cross and inadequate, but the narrator concludes that despite her modesty, she did indeed deserve the praise.