She is a very practical, no-nonsense young woman, and wishes for Alice to be the same way.
Role in the film
In the film, she is first introduced reading Alice's history lesson in the park near the river bank. Halfway through, she notices Alice's lack of attention. Alice tells her that there is simply no need for a book without pictures, but her sister returns that there are a great deal of books without any pictures. She did appear to express a mild amusement at Alice's musings of her own world that had books with only pictures. Alice then sneaks away from her and follows the White Rabbit, thus beginning her adventure. She is not seen until the end of the film when she wakes Alice from her dream of Wonderland. At first, she is disappointed at Alice for dozing off and dreaming up such nonsense, but she is able to accept her little sister's wild imagination. They, along with Dinah, then head home for tea.
In some Little Golden Books and the Broadway Jr. Show Alice in Wonderland Jr., her name is Mathilda.