Like the rest of her family, D.W. is an anthropomorphic aardvark. Her brown hair and the shape of it comes from. She has brown hair in the form of a Bob cut, which is up to her cheeks plus, she has bangs. She wears a white long-sleeved blouse, a frilly fuchsia knee-length sleeveless dress, frilly cream-colored or white panties, a matching camisole, light pink tights and cyan-blue strapped Mary Jane shoes. D.W. also has many alternate outfits: Her footsie pajamas, pink frilly swimsuit, red polka dot dress (usually worn to formal occasions), her Arthur outfit, gymnastics suit, and many more. In some of the books, she wore pink overalls. In the episode "Double Tibble Trouble", she wore green overalls. In the summer she either wears a dress and a short sleeved shirt, or shorts and a blue T- Shirt, like in "D.W.'s Deer Friend", when she went camping. She also wears her blue T- Shirt with gray jeans. In the episode "All Fired Up", she wore purple overalls, with green pockets.
Despite being nauseatingly adorable and unbearably beautiful, D.W. is often annoying to her big brother (he considers her a pest) and sometimes, she takes pleasure in getting him in trouble, but deep down, she truly loves him. D.W. gets along well with most of her friends, but often becomes very dramatic when things don't go her way and sometimes becomes too bossy. She is known for her many short-lived obsessions and temper tantrums, two of her longest-lived ones being Mary Moo-Cow and the song, "Crazy Bus" both of which annoy Arthur to no end. She also has a very pretty imaginary friend named , whom she plays with and confides her problems to when no one else is around. She hates her full name and she has everyone call her "D.W." for short instead. She also seems to be very protective of Kate. Based on Marc Brown's real-life younger sister Kim Brown , D.W.'s character reflects (possibly Marc's) view of a bratty younger sibling who often makes things more difficult than they need be. Kim travels the country, presenting at schools telling her story as "The Real D.W." Being a preschooler, she often doesn't understand the definition of words and she tries to use complex words for her age, such as "taxpaying" and she accidentally turns them into words like "taxipaying". She also doesn't grasp important topics like where babies come from, in which she thought that they come from a large baby store. D.W. has a fear of octopuses and once she endured a short-lived fear of fire drills (and anything else related to fire). She is a very picky eater and once, she had a profound hatred of spinach. She once had a snowball which was stolen from the fridge (apparently by aliens) and she frequently blames Arthur for its disappearance, which is a running gag. She did this continually until Arthur tried to make her feel better by giving her what looked like her snowball, at which point D.W. admitted that he couldn't have taken it from her. D.W. is also very gullible. She believes that anything she sees on TV that is enhanced to look good is good. This is suggested in "D.W. Goes to Washington," where Arthur brings up the story when they went to "Santa's Igloo" where you shared a sundae with "Santa" and you had to buy a sundae to share it with the guy in the Santa costume. Also, she is frequently tricked by the Tibble Twins into doing silly things that get her in trouble, even though she has acknowledged many times that the Tibbles always lie.
When D.W. was a baby, she originally had just clumps of hair, but in later seasons, it depicted her with a similar, but shorter, hairstyle. During her babyhood, she wore a pink shirt, white disposable diapers, and pink socks. She also had the same crib that had eventually become Kate's crib.
In the Living Books computer games, she had a brown complexion and orange hair in Arthur's Teacher Trouble and then had a pale complexion and light brown hair in Arthur's Birthday, and she wore a purple shirt instead of a white one while wearing a jumper or overalls. It was likely because of color and tone restrictions during the 16-bit era of computers and software. In these two games, she was voiced by Helena McAnham and it was by far her only female voiceover in the series, and the cartoon show that first aired in 1996, a few years after the first release of those two Living Books games had always voiced her with a male voiceover. D.W. was originally voiced by Michael Caloz in the first three seasons. Oliver Grainger took his place for Seasons 4-6, then Jason Szwimmer took over for Seasons 7-10. As of Season 11-15, she is voiced by Robert Naylor and Sofia Sacha Naylor provides her singing voice in Arthur's Perfect Christmas and "In My Africa." Since Season 16, she is currently voiced by Jake Beale. In the later games during the 32-bit era of computers and software (such as Arthur's Thinking Games), her appearance was the same as she looks in the cartoon show.