"Apartment 303" is the residence originally home to Troy and Abed which they moved into during their third year at school. Over the years it has been the home to various members of the study group. Not long after Troy and Abed had their housewarming party Annie was invited to move in with them. In his fifth year at school Troy moves out to pursue an incredible opportunity. In her sixth year at school, a homeless Britta is invited by Annie and Abed to move in with them. The apartment's first appearance was in the Season Three episode "Remedial Chaos Theory".
In the "Season One" episode "Pascal's Triangle Revisited", Troy's father kicks him out of the house, and he tries to get Abed to let him move into his dorm. Abed refuses, and explains that in this point in their relationship such a move would be "jumping the shark"; them constantly being together could cause them to end up hating each other. Troy eventually understands his reasoning and accepts a previous offer from Pierce to move into his mansion. He stays throughout "Season Two" although he still remains close friends with Abed even staying over in his dorm one night and building a blanket fort. It's assumed after the events of the finale "For a Few Paintballs More" and Pierce's quitting of the study group that he moved out of the mansion between then and the "Season Three" premiere "Biology 101". It is at the first study group meeting of the year that he and Abed announce that they will be moving in together.
- "Remedial Chaos Theory": Troy and Abed throw a housewarming party and invite the study group. In the "Prime Timeline" the party is a big success. Abed extends an invitation to Annie to move in with them which she is happy to accept.
- "Studies in Modern Movement": The study group, sans Jeff, help Annie move into the apartment from her place above Dildopolis.
- "Foosball and Nocturnal Vigilantism": Annie accidentally destroys Abed's new special edition Dark Knight DVD, and Abed once again assumes his Batman persona to investigate the matter.
- "Regional Holiday Music": Abed convinces Troy to join the Glee club by performing the "Christmas Infiltration" rap with him inside their blanket fort.
- "Contemporary Impressionists": Troy gets angry with Abed for hiring more impressionists after he and the study group helped to settle his earlier debt with Vinnie.
- "Urban Matrimony and the Sandwich Arts": Troy and Abed" have an all night session in The Dreamatorium to purge themselves of weirdness before Shirley's wedding.
- "Digital Exploration of Interior Design": Their apartment building is being tented for termites so Troy, Abed and Annie must live elsewhere temporarily. Annie stays in the sleep study lab., while Troy and Abed build a pillow fort at the school, which soons begins the chain of events that lead to the Pillow and Blanket Fight.
- "Origins of Vampire Mythology": Troy, Abed, and Annie help Britta by keeping an eye on her in their apartment away from her ex-boyfriend Blade.
- "Course Listing Unavailable": The study group gathers at the apartment after being expelled from Greendale, and The Darkest Timeline is prevented by Troy who raises everyone's spirits by reminding them that they still have each other.
- " First Chang Dynasty": At the apartment, the study group are unsuccessful at convincing Officer Cackowski that Faux-by has replaced Dean Pelton. Later, Murray shows up to the apartment to bring Troy to the Greendale Air Conditioning Repair School.
- "Introduction to Finality": Abed goes into The Dreamatorium and is "taken over" by Evil Abed.
- "History 101": Britta, Annie and Troy are in the apartment trying to get Abed to overcome his anxieties for the study groups last year set school together.
- "Conventions of Space and Time": Britta goes through an elaborate escape plan from Troy's room to the hallway outside the apartment to keep their hook ups a secret from Abed.
- "Basic Human Anatomy": Troy wakes up in his room and role plays that he and Abed have switched bodies.
- "Advanced Introduction to Finality": Abed meets Evil Abed who explains that he lives alone since Evil Troy moved out.
- "Introduction to Teaching": Abed fills the apartment with Nicholas Cage sticky notes and strings, to the dismay of Troy and Annie.
- "Geothermal Escapism": Troy moves out of the apartment after he is bequeathed Pierce's shares of Hawthorne Wipes on the condition that he sail around the world.
- "VCR Maintenance and Educational Publishing": Annie and Abed come to the realization that they have no money to pay for the apartment. Abed suggests Rachel and Annie suggests her brother, Anthony. However, in the end they decide to find another roommate on craigslist.
The aparment is located at 3624 Dresser Avenue in Colorado, it is numbered room 303 as a reference to the difference in the production code and air number due to "Remedial Chaos Theory" airing after "Competitive Ecology" despite being filmed before.
The apartment is numbered 303 and is located on the third floor of the complex. It has central heating, is equipped with an intercom system to screen visitors, and has a fire escape. The apartment itself is a two bedroom residence with a kitchen, a dining area, a living room area, and one bathroom. Annie sleeps in the main bedroom, while a blanket fort is set up by Troy and Abed to be an additional bedroom. The second bedroom was used as a playroom called "The Dreamatorium" before Abed dismantled it in Introduction to Finality. It is now Troy's bedroom. The apartment is decorated with an Indiana Jones diorama, pictures of Troy and Abed as well as various posters (see Main article: "Abed's posters).