Joan Walden is a major character in the 2003 Dr. Seuss live-action film, The Cat in the Hat. In the film, Joan Walden is portrayed by actress Kelly Preston. She is a single mother of two children, and was the love interest of her greedy and self-indulgent neighbor Larry until she found out his true intentions.
Joan is the single-mother of Conrad and Sally. She is first seen working at the Humberfloob company as she is announced as the host of the office party. After Conrad does another dangerous stunt and lets Nevins out, Larry Quinn gives the dog back as his way of return the feelings he (supposedly) has for her and tells Joan that if Conrad gets into trouble again, he will be sent to military school.
As Joan is called back to the office for one more thing by her boss, Mr. Humberfloob, she calls Mrs. Kwan to babysit Conrad and Sally and also tells Conrad and Sally to not enter the living room because the party is going to be there.
After the Cat in the Hat appears, he accidentally ruins Joan’s best dress for the party and lets Thing 1 and Thing 2 not only mess up the dress, but also the entire house. Larry calls Joan to tell her that Nevins escaped again and after he returns Nevins to Joan again, he will send Conrad to military school. After the Cat successfully tricks Larry into signing a paper and quickly flees with the kids along with Nevins, Larry tries to go after them and tells Joan about a cat in the hat; however, Thing 1 and Thing 2 disguised themselves as police officers to distract her and Larry. Larry tries to follow them and catches Conrad and Sally, but the Cat scares him, causing him to fall into the purple river. After Conrad locks the crate and catches Sally, the house becomes a complete mess and Conrad tells the Cat to leave. The Cat successfully cleans up the mess with a great cleaning machine before Joan comes home.
After the Cat leaves, Joan comes in the newly-cleaned house to see that Conrad and Sally are listening to her rules. Larry explains that Conrad and Sally destroyed the house and also tells her that he has busted the kids. However, Joan doesn’t see the house destroyed and thinks Larry is acting weird. She asks him to leave and will not marry him. She tries to kick him out of the house and she and her kids embrace. But Larry intercepts and asks her to marry him and send Conrad to military school ten minutes before the guests arrive. But he is kicked out again, and the party is shown to be a success. Towards the end of the film, after the successful party, Joan, Conrad and Sally have fun by jumping on the couch.