| 31223 EN | Of Things Not Seen | Aker, Don | 6.1 | 7.0 |
| 900106 EN | Officer Buckle and Gloria (MH Edition) | Rathmann, Peggy | 3.4 | 0.5 |
| 32539 EN | Oh No, It's Robert | Seuling, Barbara | 3.8 | 2.0 |
| 9038 EN | Oh Say Can You Say? | Seuss, Dr | 4.0 | 0.5 |
| 9039 EN | Oh, the Places You'll Go! | Seuss, Dr. | 3.3 | 0.5 |
| 9040 EN | Oh, the Thinks You Can Think! | Seuss, Dr. | 1.8 | 0.5 |
| 6080 EN | Old Black Fly | Aylesworth, Jim | 1.4 | 0.5 |
| 65 EN | Old Mother West Wind | Burgess, Thornton | 5.2 | 3.0 |
| 6081 EN | Old Woman and Her Pig, The | Kimmel, Eric A. | 2.4 | 0.5 |
| 6581 EN | Old World Monkeys (Zoobooks) | Elwood, Ann | 5.4 | 0.5 |
| 66 EN | Old Yeller | Gipson, Fred | 5.0 | 5.0 |
| 284 EN | Oliver Dibbs to the Rescue! | Steiner, Barbara | 4.0 | 4.0 |
| 9041 EN | On Beyond Zebra | Seuss, Dr. | 4.2 | 0.5 |
| 6082 EN | On Mother's Lap | Scott, Ann | 2.0 | 0.5 |
| 128 EN | On My Honor | Bauer, Marion Dane | 4.7 | 2.0 |
| 900439 EN | On the Ball (MH Edition) | Burgan, Michael | 4.5 | 0.5 |
| 67 EN | On the Banks of Plum Creek | Wilder, Laura Ingalls | 4.6 | 8.0 |
| 900400 EN | On the Bus with Joanna Cole (MH Edition) | Cole, Joanna | 5.1 | 0.5 |
| 630 EN | On the Far Side of the Mountain | George, Jean Craighead | 4.5 | 6.0 |
| 900101 EN | On the Go! (MH Edition) | Time-for-Kids-Editors | 2.2 | 0.5 |
| 11184 EN | On Top of Spaghetti | Glazer, Tom | 2.1 | 0.5 |
| 900435 EN | On Track (MH Edition) | Rowland, Della | 4.6 | 0.5 |
| 9785 EN | Once There Was a Tree | Romanova, Natalia | 3.3 | 0.5 |
| 44824 EN | One Eye Laughing, the Other Weeping: The Diary of Julie Weiss | Denenberg, Barry | 5.6 | 6.0 |
| 241 EN | One-Eyed Cat | Fox, Paula | 5.4 | 7.0 |
| 5488 EN | One Fine Day | Hogrogian, Nonny | 3.5 | 0.5 |
| 9042 EN | One Fish, Two Fish, Red Fish, Blue Fish | Seuss, Dr. | 1.7 | 0.5 |
| 900084 EN | One Good Pup (MH Edition) | Asch, Frank | 0.7 | 0.5 |
| 5239 EN | One of the Third Grade Thonkers | Naylor, Phyllis Reynolds | 5.1 | 4.0 |
| 6083 EN | One of Three | Johnson, Angela | 2.4 | 0.5 |
| 900592 EN | One Year in the West (MH Edition) | Smith, Geof | 5.9 | 0.5 |
| 68 EN | Onion John | Krumgold, Joseph | 4.5 | 8.0 |
| 31214 EN | Onlyhouse, The | Toten, Teresa | 3.6 | 4.0 |
| 900393 EN | Open Wide, Don't Bite! (MH Edition) | Time-for-Kids-Editors | 3.1 | 0.5 |
| 900569 EN | Opera, Karate, and Bandits (MH Edition) | Nhuong, Huynh Quang | 5.5 | 0.5 |
| 900206 EN | Opt: An Illusionary Tale (MH Edition) | Baum, Arline/Joseph | 2.6 | 0.5 |
| 6582 EN | Orangutans (Zoobooks) | Wexo, John Bonnett | 5.8 | 0.5 |
| 746 EN | Ordinary People | Guest, Judith | 4.1 | 9.0 |
| 5222 EN | Original Adventures of Hank the Cowdog, The | Erickson, John R. | 4.5 | 3.0 |
| 6583 EN | Ostriches, Emus, Rheas, Kiwis & Cassowaries (Zoobooks) | Elwood, Ann | 4.9 | 0.5 |
| 14640 EN | Other Side of the Bridge, The | Hanel, Wolfram | 2.9 | 0.5 |
| 35294 EN | Our Only May Amelia | Holm, Jennifer L. | 4.8 | 7.0 |
| 900116 EN | Our Soccer League (MH Edition) | Solomon, Chuck | 2.0 | 0.5 |
| 631 EN | Outlaw Red | Kjelgaard, Jim | 6.6 | 8.0 |
| 11185 EN | Over and Over | Zolotow, Charlotte | 3.9 | 0.5 |
| 129 EN | Over Sea, Under Stone | Cooper, Susan | 5.4 | 12.0 |
| 6135 EN | Over the Green Hills | Isadora, Rachel | 2.9 | 0.5 |
| 900576 EN | Over the Top of the World (MH Edition) | Steger/Bowermaster | 5.5 | 0.5 |
| 32700 EN | Owen Foote, Soccer Star | Greene, Stephanie | 3.1 | 1.0 |
| 900099 EN | Owl and the Moon (MH Edition) | Lobel, Arnold | 2.2 | 0.5 |
| 5531 EN | Owl and the Pussycat, The | Lear, Edward | 2.5 | 0.5 |
| 5532 EN | Owl Moon | Yolen, Jane | 3.2 | 0.5 |
| 6584 EN | Owls (Zoobooks) | Biel, Timothy Levi | 4.9 | 0.5 |
| 542 EN | Ox-Bow Incident, The | Clark, Walter | 5.4 | 12.0 |
| 6084 EN | Ox-Cart Man | Hall, Donald | 4.5 | 0.5 |