Martin, Ann M., 1955- Baby-sitters Club #31

"This book was originally published in paperback by Scholastic Inc. in 1990"--Title page verso

"Now that Dawn and Mary Anne are friends and sisters, Dawn wants them to do everything together. But living with Mary Anne isn't exactly what Dawn expected. Mary Anne brags about having a date to the school dance, her kitten throws up on the rug, and she hogs Dawn's baby-sitting jobs! Dawn's always wanted a sister. Instead, she got Mary Anne, the wicked stepsister of Stoneybrook!"--Back cover

"Dawn thought having a sister was supposed to be fun... "--Cover

Includes an excerpt from the next book from The Baby-sitters Club