The first chapter introduces the character of Dorothea Brooke. She and her sister Celia are orphans in the care of their uncle, Mr. Brooke. Although she is from a wealthy family, Dorothea prefers to dress plainly. Still, she possesses "that kind of beauty that seems to be thrown into relief by poor dress." Dorothea longs to live an ascetic life devoted to some great project for improving the world. She is forever attempting to persuade her uncle to spend money to improve the lot of the tenants on his estate.

Mr. Brooke fears that her Puritan energy will hinder her marriage prospects. However, many men find her bewitching, especially on horseback. Dorothea does not realize this; she assumes that Sir James Chettam's frequent visits to Tipton Grange, the Brooke estate, have nothing to do with her. She believes he wishes to marry Celia.

Celia works up the courage to ask Dorothea to divide their late mother's jewelry. She fears that Dorothea will think her request is vain and frivolous. Dorothea takes only an emerald ring and a matching bracelet for herself and allows Celia to take the rest. Innocently, Celia asks whether Dorothea will wear the ring and bracelet in company. The question offends Dorothea.

During a small dinner party at Tipton Grange, Sir James informs Mr. Brooke and Dorothea of his plans to improve conditions for the tenants on his estate. Mr. Brooke declares that he spends far too much on such endeavors. Dorothea disagrees and points out with sharp wit that Mr. Brooke spends large sums on entertainment and little on socially responsible projects. Her well-spoken retort catches the attention of Mr. Casaubon, a middle-aged scholar and clergyman. Dorothea admires Casaubon for his dignified, intellectual conversation. Celia knows that Sir James wishes to marry Dorothea and believes that Casaubon is old, boring, and ugly. For her part, Dorothea thinks that Sir James is silly.

Casaubon and Dorothea begin to spend more time in conversation. He admires her because she does not care for the frivolous and trivial things in life. She admires him for his "great soul." She wants to become his wife. Sir James attempts to please Dorothea by showing interest in her "plan for cottages." Dorothea devotes her spare time to drawing plans for better housing for the tenants on Brooke's estate. Sir James admits that Brooke is unlikely to spend the money for the project, but he states that he himself would like to follow her plans at Freshitt, his own estate. Dorothea is delighted, and the two of them set to work on putting the plan into action.

Celia informs Dorothea that Sir James wishes to marry her; Dorothea reacts with utter disbelief and plans to discourage him. However, Mr. Brooke arrives to tell her that Casaubon has asked him for her hand in marriage. Dorothea is overjoyed and accepts the proposal right away. Brooke does not understand why she prefers Casaubon over Sir James, but he wishes to allow her to make her own choice. Dorothea informs Celia of her engagement to Casaubon. Celia reacts with anxiety and sadness at the news.