ANNE TYLER once confessed that her idea of heaven would be to live on a Main Street inhabited by all her characters. More and more, Tyler's readers might agree with her vision as with each new novel - this is her 12th - she adds another endearing, if often eccentric, family to her fictional world, making good on her promise that "really what it seems to me I'm doing is populating a town."Tylertown, as her mythical village could be called, boasts a full complement of memorable families - the Learys of "The Accidental Tourist," the Tulls of "Dinner at the Homesick Restaurant," and the Morans of "Breathing Lessons," which earned Tyler a Pulitzer Prize. But few families appeal with more heartbreaking charm than the Bedloes, the "ideal, apple-pie household" at the center of "Saint Maybe." With three good-looking children, a steady succession of grandchildren, and a small menagerie of pets filling their modest house on Waverly Street in Baltimore, Doug and Bee Bedloe "believed that every part of their lives was absolutely wonderful." Seventeen-year-old Ian Bedloe, the baby of the family, shares that sunny view of the world. ("Things would turn out fine, he felt. Hadn't they always?") Friendly, intelligent, and happily in love with his girlfriend, Cicely, Ian dreams of someday becoming famous, for one reason or another. But that is before his adored older brother, Danny, comes home with his fiancee, Lucy, a divorced mother of two who brings a mysterious past and an unsettling dash of color into the Bedloesbrown plaid family.I'd like you to meet the woman who's changed my life," Danny announces. The words prove darkly prophetic. When, in a moment of anger, Ian confronts Danny with his suspicions about Lucy, even daring to question the paternity of the baby girl Danny assumes is his, tragedy strikes. Ian's dreams get buried with his brother. Things will not turn out quite as fine as he had expected, and worse, Ian believes he must hold himself responsible. Tormented first by Danny's suicide and then by Lucy's slide into a haze of depression and pills, Ian finds a measure of solace in a storefront religion called the Church of the Second Chance. As part of the penance dictated by the group's leader, Brother Emmett, Ian drops out of college after one semester to help his parents raise Lucy's three children. A distraught Bee Bedloe sums up her sorrow: "Our lives have turned so makeshift and second-class,... and everything's been lost. Isn't it amazing that we keep on going? That we keep on shopping for clothes and getting hungry and laughing at jokes on TV? When ... our life's in ruins!" Like other afflicted Tyler families, the Bedloes do keep on going, of course. And gradually, out of the ashes of ruin slowly rises the phoenix of a reordered family life, not without its own contentment and happiness. In "Saint Maybe," as in her other novels, Tyler dramatizes a debate about the pros and cons of family life. Is the family an anchor in the storm? Or is it a shackle? Do duty and devotion hold together the members who make up a family as well as the family itself? Or do families become, not support systems, but burdens of guilt, leading to damaging sacrifices of personal freedom? This is a novel with expansive themes. "Saint Maybe" spans a quarter century, beginning in 1965, forcing Tyler to telescope events and requiring a reader to leap years. She also allows Ian - the Saint Maybe of the title - to derive more comfort than meaning from the Church of the Second Chance, and slides too quickly over his easy acceptance of Brother Emmett's strictures, from no sex to no sugar. But these are minor complaints against a novel that lives as vibrantly as its family. As she explores the myriad ways in which dreams get deferred and hopes revised, infusing the prosaic details of domestic life with honor, humor, and deep affection, it is Anne Tyler's achievement to raise ordinariness to an art form.