An Old-Fashioned Girl follows Polly Milton, a country girl who visits her wealthy friend Fanny Shaw in the city. Polly is simple, kind and sensible, and she finds the Shaw household fashionable, hurried and surprisingly unhappy. Her good example gradually affects the family. Later the story follows her as a young woman earning her own living in the city. The novel contrasts modest country values with town display, and it looks at work, friendship and independence for women.