| Author | Title |
|---|---|
| Will and Mary Pope Osborne | Knights and Castles |
| Will and Mary Pope Osborne | Space |
| Mary Osborne Pope | Magic Tree House: Winter of the Ice Wizard |
| Mary Osborne Pope | Stage Fright on a Summer Night |
| Mary Osborne Pope | Magic Tree House Stage Fright on a Summer Night |
| Mary Osborne Pope | Magic Tree House Dingoes at Dinnertime |
| Kim Ostrow | Hello Kitty's Sneaky Peaky Mystery! |
| Kathryn Otashi | One |
| Annie Owen | Bumper to Bumper |
| Ruth Owen | Half Human Monsters |
| Weldon Owen | Emergency Vehicles |
| Lisa Owings | Tiger Attack |