Maud Hart Lovelace's Betsy-Tacy Books At the Betsy-Tacy Convention in Mankato, Minn., in 1997, I disgraced myself at the trivia contest. In front of my daughter, Josephine, then 7 years old, and several hundred similarly dedicated "Betsy-Tacy" fans, I answered the question "What was the decoration on Betsy Ray's wedding cake?" with the very wrong answer: a bell. The cake was in fact decorated with a dove; the bell, it will be recalled, was hanging decoratively in the living room. This year, at the 2012 convention - "or, as I like to think of it," the mistress of ceremonies declared, "the 102nd reunion of the Deep Valley High School Class of 1910!" - I would make no such mistake. In my preparatory rereading before our third Mankato trip together, Josephine delicately suggested, I might pay particular attention to the series's nuptial and homemaking details. Deep Valley was the name Maud Hart Lovelace gave her hometown, Mankato, in the 10 Betsy-Tacy books she published between 1940 and 1955 but set much earlier, during the period of her own childhood. The first book, "Betsy-Tacy," begins in 1897, when Betsy is about to turn 5, and the series continues through "Betsy's Wedding" in 1917, with the world at war. All tell the story of an idyllic Midwestern girlhood, but also reflect the approach of the new century, from the first horseless carriages to the strutting soldiers at Betsy's boardinghouse in Munich. Like similar evocations of an earlier age and more "innocent" comings-of-age, the Betsy-Tacy books engender an almost fanatical devotion. But there's also a sense that as children's series go, they have flown below the radar, never quite developing the recognition of "Little Women," "Anne of Green Gables" and the "Little House" books. Perhaps it's because there hasn't been a movie or a TV show. The books" big cinematic moment came only tangentially in Nora Ephron's 1998 film "You've Got Mail," when Meg Ryan, portraying the owner of a small, independent children's bookstore, introduces a little girl to Betsy: "This is her best friend, Tacy, whose real name is Anastacia, and then in the next book, Betsy and Tacy become friends with Tib. . . . " That recommendation is dead-on (the little girl demands all the books) - but it's also meant to suggest that this is the kind of obscure children's-book advice you would be unlikely to get from the less-informed employee at a soulless chain store like the one owned by Tom Hanks. In truth, there is an almost exclusive, conspiratorial glee to being a Betsy-Tacy fan. Lovelace's books are a rarefied taste, known only to the cognoscenti. The Betsy-Tacy Society, founded in 1990, has in some ways played to this, with its trademark catchphrase, "I thought I was the only one!" This is a society of zealots, delighted to discover sisterhood and solidarity. There were hundreds of us readers, nearly all women, chasing down "important sites" in Minneapolis and Mankato on a hot weekend in July. We visited "Betsy's House" and "Tacy's House," where Lovelace and her real best friend, Frances Kenney, known as Bick, lived as children, right across the street from each other. The Betsy-Tacy Society now owns both houses, which have been designated national literary landmarks, and Betsy's house has been evocatively furnished and restored. We took turns crowding into the little one-bedroom apartment where Lovelace and her husband had lived, the model for the newlyweds" first apartment in "Betsy's Wedding." (There's a dove on the cake, do you hear me? A dove!) The current tenant looked on in good-natured amusement, but the owner of another Betsy-Tacy-related home a few blocks away had apparently asked in no uncertain terms to keep the groups off her property. I happened on Betsy and Tacy and Tib while growing up in New York City in the 1960s. I read through the first four, the "childhood" books, with their delicate drawings by Lois Lenski, the brilliant illustrator whose great subject was regional American childhood, and then passed them on to my own daughter when she was about 5. Perri Klass is a professor of journalism and pediatrics at New York University. She writes the "18 and Under" column for The Times.