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.

When Christine learns that Richard and "new" Christine are enjoying an intimate relationship, she becomes determined to make her own conquests. After several failed attempts to meet eligible men, she finally runs into a guy named Stan at the grocery store. Unbeknownst to Christine, Stan is a father at Ritchie's school who is known as "Sad Dad."

When Christine learns that her close friends, Barb and Pete, are responsible for introducing Richard to his "new" Christine, she allows them to set her up on a blind date of her own. After a series of unsuccessful dates, she finds the possibility of love in the strangest of places. Meanwhile, Matthew takes Ritchie to swimming lessons.

Richard learns from a gloating Matthew that Christine is out enjoying her fifth date with a new beau, Burton, so he does what any self-respecting ex-husband would do: he sabotages the happy couple's goodnight kiss and insults Burton with lawyer jokes. But when he tries to make it up to them by inviting Christine and Burton to dinner with him and "new" Christine, his best-laid plans go awry.

After 10 dates, Christine faces a critical moment in her relationship with Burton. Will she or won't she? Let him in the house, that is, to meet her son, Ritchie. She eventually relents, only to be thrown for a loop later.

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's former marriage counselor comes into the gym, leading to some awkward moments between the two women. When Christine mentions this to Richard, his cryptic reaction leads her to question whether it was in the counselor's best interest to encourage their divorce. Meanwhile, Matthew finds Christine's wedding video in a box of old photo albums, and Christine takes a trip down memory lane.

Christine objects when Richard and "new" Christine want to take Ritchie to a Rolling Stones concert. Fearing that Ritchie is too young to be exposed to sex, drugs and rock and roll vices on display at a Rolling Stones concert, Christine initially forbids it. Eventually, she relents but immediately regrets her decision and, in a panic, goes to the venue with Matthew to see if she can sneak into the concert in order to keep tabs on Ritchie.

Shut out once again by the cliquey, judgmental moms at Ritchie's school, Christine runs into a down-to-earth working woman, Belinda, who invites her over for a drink after work. Belinda's job, however, isn't quite the type of position Christine expected her to hold, which throws yet another wrinkle in her attempt to fit in with the other school parents.

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.

Since "New" Christine broke up with Richard, he's been spending a lot of time at her house, leading Ritchie to believe that his parents are back together. When Christine tells Richard that Ritchie told this to his new teacher, Mr. Harris, Richard suggests that they give their relationship another try.

Richard tells Christine that the reason he has good luck with women is that he "says yes to life." When Christine meets a good-looking man after paying a surprise visit to New Christine, she decides to break out of her mold and says yes when he asks her out to dinner.

Christine is stunned to find out the man she's seeing, New Christine's father, is also a grandfather.

Ritchie goes to church with Richard and new Christine without consulting his mother first, leaving old Christine to explain and explore her aversion to organized religion.

Barb moves in with Christine after deciding to divorce her husband. This forces Matthew into Ritchie's room, where he discovers his nephew has some odd habits.

Christine runs into Stan again and is unable to resist him, despite her best efforts. She asks Matthew to help keep Stan away from her, but her brother is having attraction issues of his own--his latest girlfriend refuses to leave.

Christine's attraction to Ritchie's teacher causes a scene at a school fund-raiser--especially after she wins a playdate with the man.

Christine makes sacrifices so she can pay for Ritchie's school tuition.

After Richie begins showing more interest in spending time with Richard and then does a bad job on his school homework project, Christine contemplates bailing Richie out in an attempt to win him over again.

Christine has trouble working with Barb at the gym and feels pressure at home to find a nanny for Ritchie when Richard is unavailable to care for him due to a trip with New Christine.

When Christine's environmentally-friendly hybrid car and Marly's gas-guzzling monster SUV hit one another, it becomes a bigger dispute than simply who hit whom. While her car is in the shop, Christine is forced to go against her principles and rent a luxury SUV when no other car is available.

Richard want Ritchie to learn the value of competition and male bonding, and signs him up for soccer. Christine disagrees, but then has her own competitive urges when fighting with Richard for attention from Mr. Harris.

Christine can't help but meddle in Matthew's love life when she meets his ex-girlfriend at a party. Meanwhile, Richard hopes to get Ritchie enthused about his contracting job.

Jealous that New Christine benefits from all the positive qualities she instilled in Richard during their marriage, Christine spites her by revealing to Richard that she gave New Christine the idea for the birthday gift she gave him.

Christine finds out her new sleep medication caused her to embarrass herself over the phone.

Christine finds out Richard's brother is gay, but not until after sleeping with him.

Christine vows to become more aware of politics when Richard scolds her about her indifference towards an upcoming election setting a bad example for Ritchie.

Trying to send an e-mail to Barb about Mr. Harris, Christine ends up sending it to all the parents from school, nearly costing him his job.

When Christine learns that Richard has been hired to remodel "meanie mom" Lindsay's bathroom, she can't help but intervene to make sure he doesn't screw up the job and risk their reputation at Ritchie's school. Additionally, she and Richard are at odds over which of them gets to be the one to give Ritchie the sex talk.

The stresses of going to a wedding with Richard and Barb are multiplied by Christine's agreeing to be designated driver, depriving her of some much-needed alcohol.

On their way to Ritchie's desert camping trip, Christine, Richard, Matthew, and Barb stay at a seedy motel and get on each others' nerves.

Christine realizes that one reckless evening may have jeopardized her chance to begin dating Mr. Harris.

Christine and Mr. Harris try to establish a relationship before having sex, but Barb gives her pause. Matthew is horrified when he sees his med school cadaver was a neighbor.

Insecurity over a waitress flirting with Daniel sends Christine to a plastic surgeon's office.

Roles reverse when Christine's dubbed a "meanie mom" by a father at Ritchie's school who finds Marly and Lindsay to be to his liking.

Ritchie's soccer match leaves Christine running late for an event she's supposed to be attending with Mr. Harris.

Christine tries to get over breaking up with Daniel. Matthew learns the source of his intimacy issues is not his mother, but Christine.

Christine hesitantly allows New Christine to arrange a blind date for her and finds her intuition against the idea was spot on.

Christine finds herself forced to feign happiness when she covets the house Richard and New Christine have purchased.

Christine hopes acting a bit more wild will stop Barb thinking she's uncool.

Christine tries to forbid Barb and Matthew from letting a night of passion bloom into a full-blown relationship.

Christine tries to control her hormones when her gynecologist says she may be entering perimenopause.

Christine offers to marry Barb to help her stave off deportation. Meanwhile, Richard looks to pop the question to New Christine.

Richard begs Christine for the return of her old wedding ring which was an heirloom from his mother, in hopes of giving it to new Christine when he proposes.

Barb's profile in a business journal brings in new clientele.

Christine has been burning the candle at both ends -- working hard and trying to be a good mom. Ritchie decides he wants to join the reptile club at school and tells Christine all she needs to do is get the permission slip in on time. When Christine realizes that she's forgotten yet again, she asks the Reptile Guy (Jeffrey Tambor) to make an exception. He says the only way he'll consider is if Christine will go on a date with him. As creepy as he is, Christine is determined not to let Ritchie down, and so she complies.

Christine is distraught when Ritchie stops saying "I love you" to her. When she reveals her distress to Matthew, she also admits that she's been sleeping in Ritchie's room every night. Matthew tells her that if she's not careful, Ritchie will end up like him -- he can't go to sleep without talking to their mother. They spend the night helping each other break these habits.

Christine and Barb prepare for a casual, non-relationship-seeking double date with two guys they meet at a video store, but jealousy arises when only one of them gets asked out for a second date.

Christine and Richard have a dinner date with her new boyfriend, Patrick, (Tim DeKay a.k.a. Bizarro Jerry on "Seinfeld") returns as her date.

A talent scout caught Ritchie's great school performance and he liked what he saw and offered him a audition to do a TV commercial, much to a thrilled Christine, but Richard won't approve of it and refuses to like him go.

Christine thinks she has the perfect boyfriend, until he has a 'bizarre' reaction to her competitiveness after losing to her at tennis.

Over a Thanksgiving visit, the discovery of a shared secret gives Christine a way to negate one of her mother's criticisms.

The parent company of Christine and Barb's gym franchise comes for an inspection and discovers that they have broken a contractual clause, risking the entire business. New Christine wants Richard to get a vasectomy.

The girls change their building into a spa after learning that they can't get a loan to keep their gym afloat.

Christine tries to make a good impression at the Parents Orientation. However, her behavior is anything but good when she recognizes one of the fathers as the boy she knew in junior high.

New Christine loosens up during a bachelorette party Christine and Barb throw in Vegas.

With Barb and Mathew moving out and Ritchie leaving for science camp, Christine wants to prove she can take care of herself.

After Ritchie hurts himself at a skateboarding party, Christine accuses Richard of bad parenting, and they begin competing to prove each other wrong. Matthew gets involved in a rebound relationship.

At first Christine is impressed when another mother considers her a "rock," but soon finds it's exhausting being responsible.

Christine and Richard help Marly and Lindsay through labor, bring back memories of Ritchie's birth which, in turn, brings back feelings for one another.

After the mothers at Ritchie's private school continue to take cheap shots at Christine, Christine decides to enroll him in public school.

Mathew gets assistance in losing weight from fitness 'expert' Christine, but she soon realizes she can't shed off a few pounds herself.

Hoping to show she's fine with Richard and New Christine's wedding, Christine feigns being in love with Todd Watski—a ruse that proves difficult to pull off when he acts boorishly at the rehearsal dinner. Meanwhile, Matthew has an encounter with New Christine's sister, Amy.

Christine finds out a secret about Jeff after they rekindle feelings for each other at Richard and New Christine's wedding. Matthew continues to date Amy, and Barb meets a possible love interest.

Christine and Matthew fly to the Bahamas to get Barb an illegal visa after she was arrested by immigration during Richard and New Christine's wedding ceremony.

A trip with Barb to retrieve some of Richard's things sees Matthew worry that New Christine isn't letting out her feelings over the wedding fiasco. Meanwhile, Christine and Richard meet up with some of their friends from college and are shocked to see how badly they've aged.

Old Christine finds a suspicious mole on her left breast, and overreacts, thinking shes dying. Meanwhile, Richard tries to negotiate with New Christine regarding their house.

An aggressive divorce attorney is hired by Christine after being convinced that Barb owes her alimony.

Christine starts seeing a therapist who's Matthew's mentor, but they are both confused on whether they want to have a professional or romantic relationship. Richard and New Christine have trouble adapting to living under the same roof.

When Ritchie is asked to a dance by the most popular girl in school, Christine believes that she is popular by association and has finally surpassed the Meanie Moms. Meanwhile, Matthew and Richard find an apartment that they want to rent together. Unfortunately, they will have to find a way to evict an old lady that lives there before they can move in.

Max decides it's time to tell Christine that she quits anything that gets too hard for her, which includes relationships, and he points out that is the reason he chose to be her therapist rather than her boyfriend.

Christine has set up a date between Richard and a gorgeous, passionate woman who works out at her gym, while Tom (Richard's friend) continues trying to woo Chrisine.

Barb, afraid that a marriage proposal is iminent, asks Christine to run interference on her next date with Dave; Richard realizes he must try to woo New Christine if he wants her back.

Christine discovers that Ritchie has become a bully at school and attempts to change his behaviour by changing her own ways.

Christine learns a juicy neighborhood secret when reluctantly attending the Christmas block party.

Christine tells her therapist, Max, that she is in love with him, but his reaction is not quite what she is expecting.

Mr. Harris returns just as Christine starts falling in love with Max.

Christine asks Richard to have a baby with her after becoming envious of Richard and New Christine's happiness in planning for theirs.

When the gym suddenly begins to become profitable, Christine and Barb find themselves coming into a lot of money. Barb decides to give to charity, and Christine must make the tough decision between splurging on a designer dress or following Barb's lead.

In an attempt to teach Ritchie's class some street smarts, Christine encourages the school administration to let them take the subway on a field trip, but she ends up being stranded at the station when the trains leaves without her.

Christine realizes that Ritchie has never been on a real family vacation, so she plans a trip to Florida, with disastrous results.

Richard is secretly planning an impromptu wedding for him and New Christine, so to help him out, Christine drags a very cranky and pregnant New Christine to a fancy salon while he puts the plan together.

When Christine is told that her five-year car lease is up, she realizes that her life hasn't evolved during that time the way she'd hoped and decides to make some major life changes, with a little help from her boyfriend, Max. Meanwhile, Matthew seeks a roommate to replace Richard.

Christine mistakes a good looking cop for a stripper, who alerts her that there is a prowler in the neighborhood. In order to feel more secure, Christine asks Matthew to stay over. Meanwhile, New Christine goes into labor, with the sole goal of avoiding having the baby arrive on Old Christine's birthday.

When Christine has Matthew and Barb throw her a "surprise" engagement party so she can get to know Max's friends, she begins to feel intellectually inferior to one particular guest, driving her to make a "surprising" decision.