Karen's Pen pal is the 20th book in the Baby Sitters Little Sister series.
Karen Brewer is getting a new pen pal named Maxine Louisa Medvin. She wants to impress Maxie to make a good friendship.
What a horrible mistake! Instead of becoming friends, they become enimies. They brag and lie to make each other sound great. It never stops! So when Ms. Colman tells Karen's class that everyones pen pal will be visiting, Karen doesn't know what to do.
When Maxie comes, it is karen's class' sports day. Maxie and karen singed up for the running ones. When they keep getting ties, they crash into each other and realize that Nothing they said in the letters were true. They become friends.