Christine's 8-year-old son, Ritchie has been accepted into a posh private school where Christine encounters two snooty class moms, Marly and Lindsay, who can't seem to grasp the concept that Christine actually works. Her 20-something slacker brother, Matthew, lives with her, but in a pinch, also serves as Ritchie's babysitter.

On the first day at Ritchie's new school, Christine is mortified to discover that her ex-husband, Richard, with whom she gets along even better than when they were married, is dating a young, nice, impossible-to-hate woman also named Christine… the "new" Christine.

Concerned about the uniformity of Ritchie's schoolmates, Christine takes it upon herself to help diversify the student body at his private school.

Following Christine's breakup with Burton, everyone expects Christine to fall apart emotionally, but she insists she is fine and looking forward to spending time with her best friend: "me." But after being humiliated while dining out alone, Christine realizes she really did care for Burton, which drives her even crazier.

Christine feels pressured to throw an extravagant party for Ritchie's 9th birthday, his first involving other children from his new private school. Recoiling from sticker shock after meeting with a ritzy event planner, Christine decides to have an arts and crafts party at her home, with mixed results.

Christine tries not to have a meltdown when her ex-husband, Richard, brings his "new" Christine with him to pick up Ritchie and take him to breakfast so that they can get to know one another. By day's end, Christine tries to pull herself together to make a good impression at parents' night at Ritchie's school, but is caught off guard when "new" Christine shows up as well.

Christine volunteers to help out at Ritchie's spring carnival and while there, she runs into the mean moms -- Marly and Lindsay -- who are clucking over the attractive father of a new student at Westbridge. Christine is excited to learn that the hot dad is her ex-boyfriend, Burton, but her hopes of re-igniting their romance are shot down when she learns Burton has a new girlfriend.