Five Little Peppers and How They Grew by Margaret Sidney, 1881.

Mrs. Pepper is a widow who lives with her five children in a little brown house.  Since her husband died when their youngest was a baby, she has supported the family by sewing.  The children try to help, but they are still very young.  The oldest, Ben, is eleven years old, and Polly, the next oldest is ten.  Their mother worries about providing them with an education, but they are barely scraping by as it is.

The family manages to get by, helping each other through crises, such as the time when everyone was catching measles.  Sometimes, they also get help from friends.

One day, when Phronsie (short for Sophronia), the youngest Pepper, about four years old, wanders off by herself, she is found by a boy named Jasper King and his dog, Prince.  They look after her until her brother, Ben, comes to take her home.  Jasper enjoys meeting the Pepper family.  He doesn’t have any siblings himself, and he thinks that it must be fun to live in a family of five.  Jasper and his father are spending the summer at a hotel in nearby Hingham, and Jasper thinks that it’s dull.  The Pepper children invite him to come visit again, saying that they will teach him how to bake like Polly does.

Jasper isn’t able to return to their house right away because he gets a cold, and Jasper’s father has been ill.  Phronsie thinks that it would be nice to make him a gingerbread man.  Together, the children make up a little basket of goodies for Jasper and his father.  The Kings are charmed by the gift, and Mr. King decides that he would also like to visit the Pepper family.  Unfortunately, due to Mr. King’s poor health and some business he has in “the city”, their visit to the area is cut short.  The Pepper children are sad that Jasper will be leaving so soon, but they invite him to return next summer.

Jasper continues to write letters to the family while he’s in the city, studying with the private tutor he shares with his cousins.  He remembers the Pepper children telling him that they don’t really celebrate Thanksgiving or Christmas because they never have enough money to buy a feast or Christmas presents.  However, he urges them to try to celebrate Christmas this year, even if it’s only in a small way.  The Pepper children make small presents for each other, like paper dolls, doll clothes, toy windmills, and whistles, and put some greenery around for decoration.  Jasper also sends the family some surprise presents.

However, Jasper’s father says that he doesn’t want to visit Hingham again because he doesn’t think that the climate there is good for him.  Instead, Jasper persuades his family to let him invite Polly for a visit.  It takes some persuasion for the Peppers to agree because Mrs. Pepper is hesitant to accept favors and Polly worries about homesickness, but they are persuaded when Jasper says that he has been unwell and that Polly’s visit would cheer him up.  In the city, Polly gets her first taste of formal education, even having a music teacher.  However, she does get homesick, so the King family sends for little Phronsie to cheer her up.  The King family is charmed by both of the girls, and Mr. King gives Phronsie many dolls to play with.

One day, when Polly realizes that she has forgotten to write a letter to their mother because she was so busy with her lessons, Phronsie decides that she will write one herself and mail it.  She doesn’t really know how to write, but she scribbles something as best she can and slips out of the house to find the post office.  She is almost run over in the street, but fortunately, Mr. King finds her and brings her home.  She isn’t hurt, but the incident worries Mr. King.

After some thought, Mr. King decides to invite the rest of the Pepper family for a visit.  The day that the rest of the Peppers arrive, Phronsie surprises a pair of thieves in the house.  The thieves get away, and the excitement from the incident makes the Peppers’ arrival less exciting than it should have been.

The Peppers fit so well into the household that Mr. King invites the family to live with them permanently.  He offers Mrs. Pepper a job as housekeeper and says that he will help the children with their education.  Mrs. Pepper accepts, and it leads to the surprising revelation that Mrs. Pepper and John Mason Whitney, the father of Jasper’s cousins, are actually cousins, making them all cousins of the King family as well.

This book is mentioned in the book Cheaper By the Dozen as a book that Mrs. Gilbreth liked to read to her children.

The book is currently available online through Internet Archive. It is part of a series.