Annamaria is the daughter of Sir John and Lady Middleton. She is three years old. She has two older brothers, John and William, and a younger sibling whose name and gender are not given.
Her mother describes her as gentle and quiet, but when she is scratched by a pin in her mother's headdress, she screams violently. Her mother and the Miss Steeles spoil her so much that she decides to keep screaming, and her mother takes her out of the room for apricot marmalade, which cheered up after a similar incident the week before.
Elinor Dashwood and Lucy Steele later work on a filigree basket for her while the rest of the company plays cards, which gives them a chance to speak further about Lucy's secret engagement to Edward Ferrars.