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Not to be confused with The Maternal Capacitance or The Maternal Combustion.

"The Maternal Congruence" is the eleventh episode of the third season of the American sitcom The Big Bang Theory. This episode first aired on Monday, December 14, 2009.


Leonard's mother, Dr. Beverly Hofstadter, has a return visit for Christmas and Leonard didn't tell her he was going out with Penny. Leonard is surprised when she comes because she told Sheldon something she didn't tell Leonard (like she didn't tell him Mitzy, his dog died). Then Beverly gets drunk and kisses Sheldon on the lips.

Extended Plot[]

The Maternal Congruence 01

Issac Newton should hang on the Christmas tree.

Penny and Leonard are decorating Leonard's Christmas tree. After being asked to contribute, Sheldon gives them a bust of Sir Issac Newton to hang on the tree partially since he was born on Christmas Day and Jesus was not.

A visit from Leonard's mother, Dr. Beverly Hofstadter (Christine Baranski), delights Sheldon and horrifies Leonard. Penny is upset because Leonard didn't mention his mother's visit to her, but that is nothing compared to when Leonard learns that Sheldon knows more about his own mother than Leonard does: Leonard learns about his parents' pending divorce, his mother's surgery, and his dog Mitzy's death all after Sheldon has known.

The Maternal Congruence 06

Beverly stealing a kiss from Sheldon.

Beverly questions Howard and Raj about their "ersatz homosexual relationship" (alluding to her last visit in "The Maternal Capacitance") and Howard tries to tell Leonard's mother that he has a girlfriend, but she doesn't seem to believe him. He asks Leonard to tell his mother, but Leonard responds, "I have no idea what you're talking about", but Leonard tells her Howard has a girlfriend after Howard makes him since Leonard knows and Howard scoffed at Leonard not knowing what's Howard's talking about.

Penny and Beverly go out drinking at the Cheesecake Factory bar and get terribly drunk. Penny tells her about her relationship with Leonard and Beverly tells her about her interest in the busboy.

When they get back to the apartment, a drunk Beverly scolds Leonard for not telling her that he is in a relationship with Penny. Leonard then confronts her about not telling him about her surgery, her divorce and his dog's death and he wants a closer mother and son relationship, so Beverly hugs him. After Leonard is gone, Beverly kisses Sheldon much to Penny's horror. Afterwards, she says that she would rather have the busboy.

The next day, Penny and Beverly are hung-over and Leonard and Sheldon are taking Beverly to the airport. Beverly asks Leonard to take care of Penny and hopes Sheldon will forgive her for her actions the previous night; however, they all decide to keep it a secret from Leonard.



  • "[It's] worth saying that the story is a good one in theory. Beverly is a good character, who acts the part really well. The idea of Leonard’s mother being cold and logical and thus Sheldon being like a surrogate parent to Leonard is interesting. It’s as if Leonard couldn't fit in in the real world and found comfort with a best friend who replicated his familial experience...Beverly kissing Sheldon was also a nice moment. Partly out of the novelty of seeing Sheldon’s first kiss and partly because it was correctly blown off...It would have been nice to see Penny comforting Leonard. I don’t think they show enough physical affection to be a convincing couple and this would have been a nice time to show some. It’s like The Big Bang Theory and I are an old married couple and we have the same argument every week." - The TV Critic's Review
  • IMDb user reviews


  • Title Reference: Leonard's mother is visiting him.
  • Chuck Lorre's vanity card [1]
  • This episode was watched by 15.58 million people with a rating of 5.6 (adults 18–49).
  • This episode aired in Canada on December 14, 2009, with 1.12 million viewers and a weekly ranking of #15.
  • Episode transcript [2]


  • This episode follows "The Maternal Capacitance" (S2E15).
  • This episode has no guest appearance by Melissa Rauch as Bernadette until the next episode of "The Psychic Vortex" (S3E12). Bernadette hasn't met Leonard's mother throughout this episode and Season 8's "The Maternal Combustion" (S8E23) until her first time of seeing her without speaking to her or standing up to her in Season 9's "The Celebration Experimentation" (S9E17), likely because there wasn't enough time for that. It is obvious Bernadette would be the only one brave enough to stand up to her. But then in Season 9's "The Line Substitution Solution", they properly met and spoke to each other for the first time ever on the show.
  • Leonard has a Sideshow Collectibles Aragorn Legendary Scale Bust with the shattered Narsil in his room. Likewise, Sheldon has a Sideshow Collectibles Legolas Legendary Scale Bust with iconic dual long knives in his bedroom, clearly seen in "The Plimpton Stimulation" (S3E21).
  • Bernadette and her waitress job are mentioned by Howard, but are not seen in this episode. There is no background appearance by Bernadette herself as the Cheesecake Factory waitress in the Cheesecake Factory scene of Penny and Beverly visiting the bar this episode. Howard explains her absence as she is out of town for her grandmother's funeral.
  • During the bar scene involving Penny and Beverly, after they ask for another round, an over-the-shoulder shot of Penny shows Beverly's glass nearly empty. It then switches to an over-the-shoulder shot of Beverly. A second later after it changes back to the shot of Penny, Beverly's glass is full. It switches back again, and after a 3rd OTS shot of Penny, it shows Beverly's glass back to how it originally was.
  • Leonard says, "Mmm, in my family, holidays weren’t so much celebrated as studied for their anthropological and psychological implications on human society." Likewise, his birthdays weren't celebrated either, as revealed in "The Peanut Reaction" (S1E16).
  • Leonard, Penny and Sheldon are watching How the Grinch Stole Christmas. Christine Baranski, who appeared later in the episode as Beverly, had a role in the 2000 live action remake of the animated movie.
  • Howard and Raj appear in only one scene in this episode. This event is the second time it happens. The first time was in "The Loobenfeld Decay" (S1E10), the third time is in "The Agreement Dissection" (S4E21) and the fourth time is in "The Ornithophobia Diffusion" (S5E9).
  • This is, by far, the only episode of the series where Raj does not have a speaking role, as he only appeared in one scene along with Howard, and as Penny and Beverly were in the room, he did not get a chance to talk; however, he does whisper in Howard's ear to communicate. It is difficult to give him dialogue if the only scene he is in includes women and he can't speak in front of them.
    • This is also the first of two episodes where a main character only appears in a non-speaking cameo, the second one being "The Spock Resonance" where it happens to future main character Amy Farrah Fowler.
  • There are a few scenes in this episode where Beverly is seen with her glasses off (whereas she wears sunglasses in the car scene at the end of this episode):
    • The scene where she takes her glasses off and says to Leonard "I am the one who’s getting a divorce, Mitzy is the one who is dead. Why are you the one making a fuss?" before Leonard leaves the sitting room and asks Penny a question about what is new in her life before Penny answers "Nothing. Not a damn thing" and shakes her head.
    • The scene at the bar of the Cheesecake Factory when she takes her glasses off from the point when she says "Oh, fair enough. What can you tell me, if anything, about that busboy’s penis?" to when she says "You go get a taxi. I’m gonna slip my business card into that busboy’s back pocket, cupping his firm, right buttock as I do so".
    • The scene at the apartment when she had her glasses off completely whilst she was entering the room drunkenly, speaking drunkenly, when she gave Leonard an uncomfortable hug and when grabs and kisses Sheldon.


[Sheldon, Leonard and Penny have just finished watching How the Grinch Stole Christmas.]
Sheldon: I found the Grinch to be a relatable and engaging character, and I was really with him right up to the point that he succumbed to social convention and returned the presents and saved Christmas. What a buzzkill that was.
Leonard: When we watch Frosty the Snowman, he roots for the sun.
Sheldon: Excuse me, but the sun is essential for all life on Earth. Frosty is merely a bit of frozen supernatural ephemera and a stolen hat—a crime, by the way, for which he is never brought to account.
Leonard: [singing "Deck the Halls"] Fa-la-la-la la-la-la-la!

[Penny has just learned that Leonard's mother Beverly is coming for another visit.]
Penny: What? Your mother’s coming? When?
Leonard: Tomorrow.
Penny: When were you going to tell me?
Leonard: Um, tomorrow?
Penny: Why were you keeping this a secret?
Leonard: Well, I just, I thought...
Sheldon: If I can interject here, obviously Leonard is concerned that his mother won’t approve of you as his mate.
Penny: Why wouldn't she approve of me? I’m adorable.
Leonard: You are, it’s just...
Sheldon: If I can interject again. Leonard comes from a remarkably high-achieving family, who have all chosen high-achieving partners. He probably feels that it’s doubtful that his mother will be overly impressed with his dating a woman whose most significant achievement is memorizing the Cheesecake Factory menu.
Penny: Hey, it’s a big menu. There’s two pages just for desserts.
Leonard: I know. And those specials, they change every day.
Penny: Okay, you know what? It’s lame when I say it, it’s just ridiculous when you pile on.
Leonard: Okay, sorry.
Penny: So what did she say when you told her we were going out?
Leonard: Um...
Penny: You didn't tell her we were going out, did you?
Leonard: Um...
Penny: Why not?
Leonard: Um...
Sheldon: Leonard, I’m no expert on meditation, but if you’re trying to calm yourself down, I believe the word is "Om".

[Leonard and Sheldon pick up Beverly at the airport. They do some catching up, and among the news items is that Leonard's brother has gotten engaged.]
Beverly: She’s a remarkable girl. The youngest appeals court judge in New Jersey and a two-time Olympic bronze medalist.
Leonard: You must be very happy.
Beverly: Why? I’m not marrying her. So, how about you? Are you seeing anyone interesting?
Sheldon: Well, I’m not sure about interesting, but...
Leonard: Not the time, Sheldon.
Sheldon: Very well. Shall we switch topics to Isaac Newton v. Gottfried Leibniz?
Beverly: It’s all right, Sheldon. I will just pretend that Leonard’s not withholding information. Although, I will point out, Leonard, that I am a trained psychiatrist and you are exhibiting the same secretive behavioral tics that accompanied your learning to masturbate.

[Back at the apartment, Beverly visits with the rest of the gang over dinner.]
Beverly: So, Howard, have you and Rajesh finally summoned the courage to express your latent homosexual feelings toward one another?
Howard: What? No!
Beverly: Why not?
Howard: Because we don’t have latent homosexual feelings toward one another.
Beverly: I see.
Howard: No, really. I have a girlfriend now.
Beverly: And where is she this evening?
Howard: She had to go out of town. Her grandmother died.
Beverly: I see. Her grandmother died.
Howard: Honest to God. Leonard, tell her I have a girlfriend.
Leonard: I don’t know what you’re talking about.
Howard: What do you mean you don’t know what I’m talking about? Tell her I have a girlfriend!
Leonard: All right. [turns to Beverly] He [making finger quotes] "has" a "girlfriend".
Howard: Her name is Bernadette. She’s working as a waitress, but she’s going to school to be a microbiologist.
Beverly: Howard, keep in mind that the more passionately you stick to this construct, the more you’re hurting your partner.

[Penny arrives, albeit a little late.]
Leonard: Mom, you remember Penny.
Beverly: Oh, yes, the waitress-slash-actress with the unresolved father issues. Has he finally come to terms with his little slugger growing breasts?
Penny: Well, he sent me a football and a catcher’s mitt for Christmas, so I’m going to say no.
Howard: If it helps, we’re all good with your breasts.
Beverly: Classic overcompensation.

[The conversation continues. Leonard gets upset about family news that comes out in passing: his parents' upcoming divorce and his dog having died. As a result, Beverly asks Penny to drive her to her hotel. As they drive, Beverly spots and comments on Penny's constantly-on "Check Engine" light. Penny changes the subject.]
Penny: So, uh, you must be devastated about your divorce.
Beverly: Oh, not at all. But I am a bit distressed to be in a vehicle that’s not subjected to regular maintenance.
Penny: Come on, I mean, you’re not upset that your marriage is over?
Beverly: Well, initially I felt something akin to grief and perhaps anger, but that’s the natural reaction of the limbic system to being betrayed by a loathsome son of a bitch.
Penny: Sure, sure.
Beverly: Thankfully, my shock was somewhat mitigated by the fact that I haven’t had intercourse with him in eight years.
Penny: [incredulous] Eight years?
Beverly: Oh, that’s nothing. I’ve been responsible for my own orgasms since 1982.
Penny: Yikes. [Beverly chuckles] What’s so funny?
Beverly: That’s exactly what I say during orgasms. Yikes.
Penny: You know what? I could use a drink. Do you want to stop for a drink?
Beverly: Oh, I don’t drink.
Penny: I do. I’ll teach you.

[Beverly and Penny are at the bar at The Cheesecake Factory doing tequila shots. As promised, Penny teaches Beverly how to drink.]
Penny: Okay, now this time try drinking it all at once.
Beverly: [slams the shot] Yikes.
Penny: I've been responsible for my own buzz since 2003. [to bartender] Another round for me and my home girl.
Beverly: I feel a spreading warmth through my extremities.
Penny: As long as you don’t feel it running down your pants, you’re fine.
Beverly: [slams another shot] Oh, that is fascinating. I’m noticing an immediate lowering of my inhibitions. For example, I’m seriously considering asking that busboy to ravish me in the alleyway while I eat cheesecake. What do you think?
Penny: Well, we are known for our cheesecake. [to bartender] Hit us again!
Beverly: Yes! If a little is good, more must be better!
Penny: Hey Bevs, guess what?
Beverly: What?
Penny: I’m sleeping with your son.
Beverly: Really! Which one?
Penny: [drunkenly stumbling over her words] The one from whom I live across the hall from.
Beverly: Well, that’s convenient. How did his penis turn out?
Penny: Oh, Beverly, I can’t talk to my boyfriend’s mother about his penis.
Beverly: Oh, fair enough. [unclips her hair and lets it fall free] What can you tell me, if anything, about that busboy’s penis?
Penny: Actually, I've only had the cheesecake. [to bartender] One more time! [back to Beverly] You know, Leonard did not want to tell you we were dating.
Beverly: Really? Well, that means he’s either embarrassed about the relationship or he doesn't care enough about his mother to tell her he’s in one. Either way, one of us should be insulted!
Penny: Well, let’s go find out who.

[Penny and Beverly return to the apartment.]
Penny: Leonard!
Beverly: Sonny-boy!
Penny: Get out here! Your mommy wants to talk to you!
[Leonard emerges from the hallway.]
Leonard: What the hell is going on?
Penny: [in a sing-song fashion] You're in trouble!
Beverly: Why didn’t you tell me you were tapping my home girl? [to Penny] Did I say that right?
Penny: Yeah, not bad, not bad.
Leonard: Are you guys drunk?
Beverly: Well, I hope so. Otherwise, why would we have stopped at Del Taco? Now, how could you not tell me you were in a relationship with this lovely, charming young woman? [puts an arm around Penny]
Penny: Oh, thank you.
Beverly: [to Penny] You’re welcome. [back to Leonard] Is it because she’s uneducated? Trapped in a menial service position?
Penny: [deflated] What the hell happened to lovely and charming?
Leonard: How come you didn't tell me that you and Father were getting a divorce? How come you didn't tell me you had surgery? How come you didn't tell me my dog died?
Beverly: [shushes him] Wait, wait, wait, wait, wait. What I hear you saying is that you want a more intimate mother-son relationship.
Leonard: I do.
[Beverly goes to Leonard and, obviously uncomfortable, gives him a stiff and awkward hug.]
Beverly: There. It’s late. Now, go to bed.
[Leonard goes back down the hallway toward the bedrooms.]
Beverly: I’m getting a warm feeling spreading through my heart.
Penny: That’s the Del Taco.
[Sheldon comes into the living room.]
Sheldon: Why is Leonard softly banging his head against his bedroom door?
Beverly: Speaking of warm feelings, come here. [She grabs Sheldon and kisses him, then spends a few seconds in deep thought.] No, I’d rather have the busboy.

[The next morning, Leonard, Sheldon and Penny take Beverly to the airport. Beverly is wearing dark glasses; she and Penny are obviously hung over.]
Beverly: Sheldon, I do hope you’ll forgive me for my inappropriate behavior last night.
Sheldon: I don’t blame you. You were intoxicated.
Beverly: Thank you.
Sheldon: I blame Penny.
Penny: I blame Penny, too. Bad Penny.
Leonard: Wait a minute. What are you talking about? What inappropriate behavior?
Beverly: I think it’s best that you not know.
Sheldon: Agreed.
Penny: Agreed.
Leonard: What the hell. Agreed.
Beverly: And I want you to take very good care of this young woman.
Penny: Oh, thank you, Beverly.
Beverly: You’re welcome. She doesn't have much in the way of career prospects. Don’t make her responsible for her own orgasms as well.
Leonard: Mother, remember when I was complaining that you don’t communicate with me enough?
Beverly: Yes, dear.
Leonard: I’m over it.
Penny: [singing the last line of "Deck the Halls"] Fa-la-la-la-la, la-la la-la.