Married couple Pete and Ellie Wagner, feeling a void in the marriage, visit a foster care center. Two social workers, Karen and Sharon, guide the hopeful parents on the steps to getting into becoming adoptive parents. The couples are brought to a fair where they have the chance to go up to kids that they are interested in adopting. Pete and Ellie walk by the teenagers, although Ellie shows hesitance over raising a teen, but one of the teens, Lizzie, informs Ellie that they all know no one wants to adopt the teens. Pete and Ellie talk to Karen and Sharon over potentially taking in Lizzie. The social workers inform the couple that Lizzie's mother is a drug addict who is currently in jail, and she set their home on fire because she left the crack pipe lit. It also turns out that Lizzie has two younger siblings, Juan and Lita. Although this seems like more of a challenge for Pete and Ellie, they agree to meet the siblings. Pete and Ellie have Thanksgiving dinner with Ellie's family, where...

Plot Synopsis:
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The film starts with Pete (Mark Wahlberg) and Ellie Wagner (Rose Byrne) showing off a fixer-upper of a home to Ellie's sister Kim (Allyn Rachel) and her husband Russ (Tom Segura) that they are trying to flip. The latter couple comment on what a dump the place looks like and how Pete and Ellie won't need a place like that since they don't plan on having kids anytime soon. It leads to an argument between Ellie and Kim due to some competition they have always felt, especially since Kim and Russ have been trying to conceive as well.

Pete later comes home from work to find Ellie crying as she is looking up children in foster care on the internet. Pete doesn't want to see it because he thinks he's going to get roped into adopting kids, but when Ellie isn't around, he starts to check the site out himself.

The couple later visit a foster care center where two social workers, Karen (Octavia Spencer) and Sharon (Tig Notaro), guide the hopeful parents on the steps to getting into becoming adoptive parents. Among them are a religious couple, a gay couple, and a woman named October (Iliza Schlesinger) who specifically wants a black teenager to turn into a pro athlete. They also listen to a guest speaker named Brenda Fernandez (Eve Harlow), who comes in with the parents that adopted her (Javier Ronceros and Rosemary Dominguez) as a teen and rescued her from a life of abuse since her birth mother and boyfriend were meth heads. Brenda's speech moves the couples into going ahead with the process.

The couples are later brought to a fair where they have the chance to go up to kids that they are interested in adopting. Pete and Ellie walk by the teenagers, although Ellie shows hesitance over raising a teen, but one of the teens, Lizzie (Isabela Moner), informs Ellie that they can hear what they are saying.

Pete and Ellie talk to Karen and Sharon over potentially taking in Lizzie. The social workers inform the couple that Lizzie's mother is a drug addict who is currently in jail, and she set their home on fire because she left the crack pipe lit. It also turns out that Lizzie has two younger siblings, Juan (Gustavo Quiroz) and Lita (Julianna Gamiz). Pete and Ellie are told that Juan is very sensitive and Lita is highly rambunctious, which is why Lizzie has had to parent them with their mother never around. Although this seems like more of a challenge for Pete and Ellie, they agree to meet the siblings.

The Wagners go to the kids' current foster home, where they live with the Muskies (John McConnell and Maureen Brennan). Ellie sits with Lita and plays a game where Lita yells at her doll with racist slurs (obviously picked up from the Muskies), while Pete tries to play basketball with Juan, only to accidentally bounce the ball off the hoop and hit Juan in the face, giving him a bloody nose.

Pete and Ellie have Thanksgiving dinner with Ellie's family, where they all make comments about never having confidence in the Wagners adopting kids. Kim and Russ are especially terrible, insinuating that the kids that Pete and Ellie pick out could have been bad influences on their own kids. Ellie has enough and decides that they will go through with the foster care to prove that they can be good parents.

Lizzie, Juan, and Lita begin to live with the Wagners. Although it is initially pleasant, it doesn't take long for things to get hectic. Lita refuses to eat anything but potato chips, and Juan reacts sensitively to every instance of trouble. Lizzie is also frequently bratty toward the Wagners, but especially Ellie. The two frequently attend support groups with the other couples for insight on what to do with the kids.

Pete's mother Sandy (Margo Martindale) comes to visit to meet the kids. She instantly wins them over by treating the whole family to Six Flags. While there, Lizzie runs off with two friends from school. She doesn't reappear until later after seeing a movie with her friends, so Ellie grounds her for not informing her or Pete as to her whereabouts.

The next day, Lizzie has the same friends come over by climbing in through the window. Ellie comes into Lizzie's room to scold her for this, and one of the girls calls her a nazi bitch, so she forces the girls to climb back out the window. Lizzie goes to join the girls, leading Pete and Ellie to follow her and argue with Lizzie. They are momentarily distracted by Juan holding a nail gun, and when Lizzie tells him to put it down, the boy drops it and a nail shoots through his foot. The Wagners take Lizzie's friend's car and rush Juan to the hospital to take the nail out.

Karen and Sharon offer solutions to Pete and Ellie for their struggles. They show Lizzie a method for which to handle her outbursts, but Lizzie is familiar with it, so she still acts bratty toward Pete and Ellie. However, Juan and Lita start to warm up to the Wagners. Lita calls Pete "Daddy" when he fixes her doll, and Ellie gets a "Good night, Mommy" from Juan after she comforts him from a nightmare. Soon, Lizzie starts to go along with the others as they partake in family activities. Pete even invites her to the fixer-upper so they can wreck things for her to take out her frustrations.

Pete and Ellie later find out that the kids' mother Carla (Joselin Reyes) has been out of prison for a few months and she wants to see the kids. The Wagners take them to meet with Carla, who thanks them for looking over them, but this upsets Ellie because Carla made it sound like they were babysitting her kids. They express their feelings about this during the group therapy, but the social workers tell them that their main goal is to keep families together. We also hear that October has found a kid, but he's short and white with red hair, which alleviates the tension in the room.

Pete and Ellie seek out the Fernandez family for help with Lizzie. They inform the Wagners that Brenda is back in rehab. Ellie snaps because they were the main reason that they went into foster care, but Mrs. Fernandez slaps her for saying that and then tells them what a process it is to really form a bond and trust with the kids. After cooling things over, the Wagners head off.

The couple is horrified when they find Lizzie taking naked selfies to send to a guy at school named Jacob (Nicholas Logan), and he sends her a dick pic. When they take the kids to school the next day, they confront a boy named Charlie (Carson Holmes) since they mistook him for Jacob after Ellie thought Lizzie was talking about him during an earlier moment. After realizing they are yelling at a kid who is NOT Jacob, they are even more horrified to find that Charlie points Jacob out to be the janitor. Pete and Ellie chase him into the school and catch him riding a zamboni. Pete punches him in the face and Ellie stomps on his balls. Jacob is arrested, but so are Pete and Ellie, leaving Juan and Lita alone in the car, while Lizzie is humiliated. When Pete and Ellie return home, they are told by Sandy that they need to reassure Lizzie that they love her, because she doesn't feel that she is loved. Ellie also takes this as Sandy feeling similarly, which is why she and Ellie have always had kind of a bumpy relationship. Ellie lets Sandy know she loves her, and vice versa, but Sandy tells the couple to change the statement they wrote for their upcoming court hearing.

The Wagners and the kids gather for a court hearing to decide whether or not the kids will go back to Carla or stay with Pete and Ellie. The judge (Valente Rodriguez) reads a statement written by Lizzie detailing the things that Pete and Ellie have done. Although Ellie tries to read her new statement, the judge won't let her. Carla is then asked whether or not she feels ready to reassume care of her children. She hesitates on the last question but says she is ready to be a mother again.

Pete and Ellie sadly start to pack things up for the kids. Juan and Lita do not want to go, but Lizzie is ready. Karen and Sharon arrive to the house to inform Lizzie that Carla is not coming to get them. They went to her house and realized that she is still using drugs, and she went back on her word over taking care of them. Heartbroken, Lizzie runs away. Pete and Ellie chase her while Karen and Sharon watch Juan and Lita. Lizzie hides in the backyard of Mrs. Howard (Joan Cusack) and cries. Pete and Ellie tell her they love her, but Lizzie refuses to come out. After Pete and Ellie go back to the house, Lizzie rejoins them. She offers to let Pete and Ellie take Juan and Lita, and that she will just occasionally visit her siblings. Pete and Ellie refuse to let that happen, and they give Lizzie their statement. She realizes they do care about her, and she embraces Pete and Ellie. Mrs. Howard wants a hug too but Ellie declines, although Lita gives her a hug.

Four months later, the family goes to a new hearing. This time, the judge clears Pete and Ellie to legally adopt the kids, and all the other foster parents, plus Pete and Ellie's families, are there to cheer them on. Everyone gathers for a big group photo.

John McConnell and Maureen Brennan who play Mr and Mrs Muskie are actually married in real life.
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'Young Pete', played by Connor Jones, and 'Pete' played by Mark Wahlberg both had many black dots drawn on their faces during filming for the football flashback in order for their faces to be matched perfectly in post-production.
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"Meatball" is played by a three-year old Bernese Mountain Dog. Prior to filming, he had completed his AKC grand championship, an obedience title, several rally obedience titles, and a dock diving title. After filming completed, he added his BMDCA and Canadian draft titles and several others, becoming a Versatility Dog in both the US and Canada.
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The film was inspired by writer/director Sean Anders' experience adopting through Seneca Family of Agencies' Kinship Center.
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The movie was inspired by the real events from the life of writer/director Sean Anders.
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Instant Family's story is based on the real life experience of director Sean Anders. Sean has adopted 3 Hispanic children.
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Isabela Moner and Mark Wahlberg previously starred together in Transformers: The Last Knight (2017).
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Mark Wahlberg played an adopted man in "Four Brothers." And a dad trying to reconnect in "Daddy's Home"
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This was the third collaboration between director Sean Anders and actor Mark Wahlberg. Their previous two films were Daddy's Home (2015) and Daddy's Home Two (2017).
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Gustavo Quiroz had a small role in another Mark Wahlberg movie, Pain & Gain (2013).
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When Karen accepts an offer for pie at the end of the film, this could be a reference to Octavia Spencer's role in The Help, which featured a notable scene involving Spencer and a pie.
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