Maggie Tulliver is the impetuous, clever younger daughter of the Tullivers of Dorlcote Mill in St. Ogg's. Maggie frustrates her superficial mother with her unconventional dark coloring and unnatural activeness and intelligence. Maggie's father often takes Maggie's side, but it is Maggie's older brother Tom upon whom she is emotionally dependent. Maggie's greatest happiness is Tom's affection, and his disapproval creates dramatic despair in Maggie, whose view of the world, as all children's, lacks perspective.
Though Tom is less studious than Maggie appears to be, Mr. Tulliver decides to pay for Tom to have additional education rather than have him take over the mill. This decision provokes a family quarrel between Mr. Tulliver and his wife's sisters, the Dodsons. Mr. Tulliver is frustrated by the snobbish contrariness of the Dodsons, led by Mrs. Tulliver's sister Mrs. Glegg, and vows to repay money that Mrs. Glegg had lent him, thereby weakening her hold on him. He has lent almost an equal sum to his sister and her husband, the Mosses, but he feels affectionately toward his sister and decides not to ask for money back, which they cannot pay.
Mr. Stelling, a clergyman, takes Tom on as a student, and Maggie visits him at school several times. On one of these visits, she befriends Mr. Stelling's other student—the sensitive, crippled Philip Wakem, son of her father's enemy, Lawyer Wakem. Maggie herself is sent to school along with her cousin, Lucy, but is called home when she is thirteen when her father finally loses his extended lawsuit with Lawyer Wakem over the use of the river Floss. Mr. Tulliver is rendered bankrupt and ill. Tom returns home as well to support the family, as the Dodson's offer little help. The mill itself is up for auction, and Lawyer Wakem, based on an idea inadvertently furnished to him by Mrs. Tulliver, buys Dorlcote Mill and retains Mr. Tulliver as a manager in an act of humiliating patronage.