The big news in Kristy's neighborhood is that the Papadakis family is getting a foster child. The Baby-sitters think taking in a troubled child is a really special thing to do. Kristy's sure the new kid will fit right in.
Only Lou (and don't call her Louisa!) turns out to be a terror. She's rough and tough, and none of the kids want to play with her.
Kristy knows she should feel sorry for Lou. But Kristy's even sorrier that she has to baby-sit for her!
Lou's aunt and uncle take Lou and her older brother Jay in. Kristy notes at Lou's going away party that Lou will be one sitting charge the BSC will never forget. Lou gets a new puppy that she names Happy, and sends a letter to Kristy.
Ann M. Martin's Dear Reader Letter
For a long time I had wanted to write a story about foster children. One day my editors and I had a meeting and tried to figure out what the next year’s worth of Baby-sitters Club books would be about. We thought of ideas for twelve books, and decided that #35 would be the story about foster kids. We also decided that a great title for this book would be Stacey and the New Kids on the Block (the “new kids” being foster kids who move into Stacey’s neighborhood).
Now, keep in mind that it takes a year to make a book. The author has to write the story, of course, and the story has to go to the printer and be set in type. Also, an artist has to make a painting for the book cover. It’s a long process! I began to work on books #32, #33, and #34. At the same time, #35 had already been advertised as Stacey and the New Kids on the Block. Lots of kids saw the ad and thought the story was going to be about the singing group, which had suddenly become really popular. Readers were very disappointed when #35 was finally published and they discovered that the book did not star Jon, Jordan, Joe, Donnie, and Danny. In fact, it wasn’t about foster children, either. My editors and I had gotten excited about an idea for a mystery, and we decided to postpone the story about the foster child until this book, Kristy and the Worst Kid Ever. And I had to answer a lot of letters about what happened to the book involving the New Kids on the Block. See what can happen when you change your mind?
Lou's hair and clothing change from the original printing to the reprint in effort to make them look more feminine in an tomboyish way.