Jessa is without a doubt the most open-minded and adventurous one out of the four.
She eventually ends up dating Adam Sackler, her friend Hannah's ex boyfriend. They end up not being as close for the last two seasons, but they tie and make up near the end of the series.
Much of Jessa's childhood is unknown. Her parent's split-up when she was little, and she has mentioned to having a strained relationship with her mother. Her father has since remarried. She also had a gay uncle who died of AIDS. Jessa also has two sisters; her older sister Minerva from her mom's side, and a little sister from her dad's. Shoshanna is her younger American cousin, who's believed to be from her mother's side of the family. She met Hannah and Marnie while briefly attending Oberlin College, and left after developing a heroin habit. She has since spent the last several years traveling the world. When Jessa thinks that she is pregnant, she decides to leave her residence in France and return to New York in order to figure out what she should do.
Jessa arrives to Shoshanna's apartment in the Pilot. She then later goes to a welcome party thrown by Hannah and Marnie. While Hannah is happy to see her, Marnie has not liked Jessa since she slept with one of her friend's boyfriends back in college. The situation is made worse when Jessa asks if Charlie (Marnie's boyfriend) is single, and letting Hannah drink Opium tea. When Marnie confronts Jessa about her irresponsible behavior, she reveals the real reason to why she came to New York.
Continuing on from the pilot, Jessa has decided to end her pregnancy. She has Marnie make an appointment for her at an abortion clinic in Vagina Panic. While on her way to the clinic, she ends up stopping at a bar, where she meets a random guy. They proceed to go into the bathroom to have sex, where Jessa discovers that she has started her period.
Jessa get's her first job as a nanny in All Adventurous Women Do. She meets and has a connection with the father Jeff. Who later forgives her for briefly losing his kids in Hannah's Diary. She meets an ex-boyfriend in Hard Being Easy. They have sex in Shoshanna's apartment while Shoshanna was still there. Afterwards, Jessa tells Shoshanna that she's not ashamed over what happened.
In Welcome to Bushwick a.k.a. The Crackcident, Jessa receives a mysterious text while at a rave with Hannah, Marnie, and Shoshanna. The text turns out to be from Jeff. She ends up abandoning Shoshanna, who accidentally smoked crack, to hang out with him. After throwing a bottle of wine at a group of male partygoers, Jeff get's jumped and has to be taken to the hospital. He later admits his attraction to Jessa, but when she rejects him, he fires her.
Following her altercation with Jeff, Jessa goes to Hannah and Marnie's apartment in Weirdos Need Girlfriends Too. She ends up forming a bond with Marnie, who's depressed over ending her relationship with Charlie, and the two end up going out. While at a bar, they get picked by a wealthy older guy named Thomas-John. They end up at John's place, where Marnie and Jessa start making out with each other. When they spill a glass of wine on his carpet, John throws them out.
Jeff's wife, Katherine, visits Jessa in Leave Me Alone. She initailly wants Jessa to come work for her again now that she and Jeff are separated, but realizes that it's not a good idea. She does however tell Jessa that the reason behind her behavior may be the fear of actually being an adult.
Jessa sends an email-blast out to Hannah, Marnie, and several other of her closest friends in She Did about a secret party she's throwing. When everyone shows up for the event, it's revealed to be a surprise wedding between Jessa and Thomas. During the celebration, her acting is very naive. While in the bathroom with Hannah, Jessa starts peeing and tells Hannah that she's wrong to think that "she's crazy and that this is too fast". Hannah asks Jessa if she is like an adult, now. Jessa and Hannah both answer "yes". The dance is going to start and Jessa didn't know the schedule so was caught by surprise. So Jessa quickly pulls up her underwear and leaves. During their vows, Jessa explains that she didn't like Thomas at first, but that his stories of finance and travel made her fall in love with him.
In the season premiere, Jessa and Thomas-John return from their honeymoon.
In I Get Ideas, Hannah sees Jessa and Thomas-John's relationship, which causes her to question her own with Sandy. Jessa is now living with Thomas-John, and he buys her anything she wants.
In It's a Shame About Ray, Jessa is to meet Thomas-John's parents. Though they are both nervous, they go to the dinner. Thomas-John's mother dislikes Jessa for her lack of work ethic and thinks she is using her son. This causes Jessa and Thomas-John to have a fight later that night, in which she leaves his in exchange for money. She goes to Hannah's house and is genuinely, visibly upset.
In the following episode, it is shown that Jessa is staying with Hannah. She tells Hannah that her first book isn't going to matter to her or readers. Hannah calls her depressed, which she denies.
In Video Games, Jessa and Hannah go to meet Jessa's father. He is extremely late in picking them up. She
and her father appear to get along fine, until the following morning. Her father and her have a brief argument, in which he promises to do better. However, the next day, he drops the two girls off at the store, and forgets to pick them up. The following morning, while Hannah is sleeping, Jessa leaves. She doesn't return until the third season, being absent for the following three episodes. Though, in the season finale, Hannah attempts to call her, and leaves a reprimanding voice mail.
At the start of the season, Jessa is staying at a rehab facility as per her grandmother's request. However, she is uncooperative and obnoxious during group therapy and antagonizes other patients. The exception is a British patient named Jasper, with whom she talks quite often. The last straw for the facility becomes when Jessa is caught having sex with another female patient, resulting n her being kicked out. She calls Hannah, their first contact in months, and asks her to give her a ride. Hannah ventures out with Adam and Shoshanna to retrieve her. Hannah tells her her behavior has not been okay, and she has to start being a better friend, to which Jessa agrees.
In Dead Inside, Jessa talks with Shoshanna about the concept of death. She reveals she had a friend named Susan who died of an overdose, and Shoshanna encourages her to visit the grave. However, Jessa learns her friend isn't dead at all, and lied to her to get away from the bad influence Jessa was.
In Only Child, Jessa begins working at a children's clothing store. She likes it at first, but becomes increasingly bored.
In Beach House, Jessa joins the girls on a weekend getaway at a beach house supplied via Marnie's mother's friend. The trip ends with the girls all arguing with each other, and then returning home.
In Incidentals, Jasper tracks Jessa down, and she relapses. The two spend their time together getting high and stealing money that Jessa's boss keeps inside a shoebox in the store.
In Role-Play, Shoshanna arranges a dinner to reunite Jasper and his daughter in order to drawn him and Jessa away from drugs and each other. Shoshanna is successful, despite Jessa's dismay.
In the season finale, it is shown that Jessa and Beedie have grown closer, and Jessa agrees to take part in helping Beedie commit suicide. However, after taking many pills, Beedie decides she doesn't want to die, and Jessa calls for an ambulance.
At the start of season 4, Jessa is still working for Beedie, who was stomach-pumped and survived. However, Beedie's daughter arrives to take her to live with her in Connecticut. Though Jessa protests, Beedie is forced to let her go and the two part very amicably. She's also very upset at Hannah's upcoming move to Iowa.
It's shown in Female Author that a friendship has begun between Jessa and Adam. They go to AA meetings together, and hang out outside as well. While walking together through the streets, Jessa stops to pee. However, the cops see and attempt to give her a ticket. After she makes rude remarks and rips the ticket, she is put under arrest. Adam, who tries to defend her, is also arrested. After release, Jessa tries to play the situation off, but Adam is very upset. He calls her reckless and doesn't want to be her friend. Very heartfeltly, she responds that she needs him to be her friend.
In Cubbies, Jessa gives Marnie disagreeable feedback on her music.
Jessa visits Hannah in Sit-In when Hannah comes back to New York and finds Adam in a relationship with an artist named Mimi-Rose. When Jessa casually reveals that she introduced Adam to Mimi-Rose since she thought Adam deserved to be happy. Causing Hannah to slap her.
When Jessa attends Mimi-Rose's art show in Ask Me My Name, she learns from Adam that Mimi-Rose's ex-boyfriend Ace wants to get her back. Which she finds particularly upsetting since she set Adam and her up because she's interested in Ace.
In Daddy Issues, Jessa is now happily dating Ace. When they run into Adam and Mimi-Rose, Ace accepts Mimi-Rose's invitation to dinner. When Ace makes it clear that he's trying to use Jessa as a way to make Mimi-Rose jealous, she breaks-up with him and leaves with Adam.
When Adam's sister Caroline goes into premature labor in Home Birth, she checks Caroline to confirm that her baby is breach. Then convinces her and Laird that they need to go to a hospital. Jessa later visits Caroline in the hospital, where she and Laird thank her for helping them in their time of need and announce their baby's name as Jessa- Hannah Bluebell Poem Schlesinger-Sackler. Making Jessa realize that she wants to be a therapist.
In the start of season 5, Jessa is making an effort to be a better person. She is pursuing a career as a therapist and is attending AA meetings regularly. In Wedding Day, Jessa is a bridesmaid in Marnie's wedding. Throughout the episode, she is calm and comforting towards Marnie, who is very nervous. After a while, she decides to go outside to smoke a cigarette and is approached by Adam, who has left the groomsmen after feeling uncomfortable. Adam laughs at Jessa's hair, which is up in curlers. They smoke together and talk about how things are going with the bridesmaids and groomsmen. Adam abruptly kisses Jessa before she pulls away saying, "I can't". Despite this, they kiss again until Adam abruptly ends the kiss and walks away. At the end of the episode, she fixes Marnie's make up and joins the rest of the bridesmaids at the ceremony.
In Good Man, though he doesn't say Jessa's name, Adam reveals to his brother in law that he has feelings for her, but calls the situation "complex". Later in the day, Jessa notices that Adam is staring at her during the AA meeting they're attending. When the meeting is over, she attempts to leave without him noticing, but he catches her. Adam wants to talk about the kiss, but Jessa tells him that they have to pretend like it never happened. He tells her that he knows that she has feelings for him, but is hiding them. Jessa tells him that even if it were true, nothing could happen between them. Adam argues with her, but Jessa tells him that Hannah is her friend and that she can't do that to her. Adam suggests that they hang out together just as friends and Jessa accepts. They end up spending the day together at Coney Island. Adam walks Jessa back to her apartment and tries to kiss her again, but she rejects him, this time telling him that even if Hannah was okay with them dating, their relationship wouldn't end well. Adam asks if they can spend time together as long as they don't touch each other, and Jessa says yes. They go into her apartment and masturbate on opposite ends of the couch while trying to avoid looking at each other.
In Japan, Jessa goes to Adam and Ray's apartment to watch Adam's guest starring role on a tv show. Jessa is very impressed by Adam's acting and compliments him, despite his embarrassment. Eventually, Ray goes to bed and leaves Adam and Jessa alone in the kitchen. Adam kisses her, but she pushes him away. She reiterates that they're just friends and leaves.
In Old Loves, it is revealed that Jessa has started avoiding Adam by attending all women's AA meetings in different neighborhoods. Adam is able to find her and confronts her, telling her that she has been ignoring his text messages as well. Jessa tells him that she's avoiding him because of Hannah and her friendship with her. Adam argues that if Hannah and Jessa's places were switched, Hannah wouldn't care about hurting her. Adam leaves and Jessa's AA counselor approaches her to warn her: "that's how I got pregnant" referring to her fight with Adam. Later, Hannah and Marnie go to Jessa's apartment unannounced and interrupt her studying. Jessa grows even more unhappy after Hannah and Marnie begin to talk about relationships. Jessa makes it obvious that she doesn't want them there, but they ignore her. That night, Jessa and Hannah go to get rice pudding. Jessa continues to be mean spirited and antagonistic towards Hannah, who has no idea why she's acting that way. Hannah finally grows angry and leaves after Jessa tells her that they should no longer be friends. She immediately goes to Adam's apartment and tells him what happened. She begins to cry and tells him that she's wanted a relationship with him for a long time. Adam reciprocates those feelings and they kiss. They eventually have sex on Adam's couch, and although it is awkward, they laugh and are affectionate towards each other. Afterwards, Jessa watches Adam as he sleeps before she lays her head on his chest.
In Queen for Two Days, Jessa and Adam have intense sex, seemingly getting over the initial awkwardness of their first time in the previous episode. Afterwards, Jessa tells Adam that her half sister, Minerva, is town and wants to have dinner with her. Adam volunteers to go if Jessa is comfortable with him being there. As they walk to meet her sister, Jessa tells Adam about Minerva. Apparently they have slept with most of the same men, except for Jessa's birth father. She also tells Adam that she's telling him this because she wants him to know that if he sleeps with Minerva, she wouldn't care because she's used to that happening with her sister. During dinner, Minerva tells Jessa that she's getting a lot of alimony from her ex husband in addition to the money she's getting from their grandmother. Jessa asks her if she can borrow some money so that she can finish college and become a therapist. She reveals that their grandmother cut Jessa off after she entered rehab. She also doesn't qualify for financial aid because she is a foreign student. Minerva tells Jessa that she's not giving her any money because she finds her to be unreliable. Jessa promises Minerva that she will pay her back as soon as she gets a job with her degree, but Minerva tells Jessa that she has seen her not follow through on too many things and that she knows her too well to lend her any money. Adam grows angry and sticks up for Jessa. He tells Minerva that she doesn't know Jessa at all and passionately talks about the good qualities that Jessa possesses. Adam tells Jessa that he will pay for her school. Jessa initially rejects the money, but Adam convinces her after he tells her that he has a lot of money thanks to some successful commercials and that he wants the money to go to something good. Jessa begins to cry and kisses Adam.
- Jemima Kirke had just given birth to her first child when the Pilot was filmed. She was also pregnant again during the Second Season, which is why her last on-screen appearance was in Video Games.
- Jessa is the only character out of the four girls who has siblings. Hannah, Marnie, and Shoshanna are portrayed as being the only child in their respective families.