| Author | Title |
|---|---|
| Barbara O'Connor | How to Steal a Dog |
| Joanne Oppenheim | "Not Now!" Said the Cow |
| Mary Pope Osborne | My Secret War : The World War II Diary of Madeline Beck |
| Mary Pope Osborne | Magic Tree House: Tonight on the Titanic |
| Mary Pope Osborne | Night of the Ninjas |
| Mary Pope Osborne | Magic Tree House Monday with the Mad Genius |
| Mary Pope Osborne | Magic Tree House: Summer of the Serpent |