"Eagleton" is the twelfth episode of the third season of the American comedy television series Parks and Recreation, and the 42nd overall episode of the series. It originally aired on NBC in the United States on May 5, 2011. In the episode, Leslie becomes angry when her former friend, the current parks director of the more prosperous neighboring town Eagleton, builds a fence through a park that runs through both Pawnee and Eagleton. Meanwhile, Leslie plans a secret birthday party for Ron, much to his chagrin.

The episode was written by Emily Spivey and directed by Nicole Holofcener. Parker Posey guest starred as Leslie's rival and former best friend, Lindsay Carlisle Shay. A longtime fan of Parks and Recreation and its star Amy Poehler, Posey had expressed an early interest in appearing on the show, and reportedly became frustrated with how long it took to be asked.

A fight scene between Poehler's and Posey's characters among piles of garbage was performed with stuntwomen during temperatures of more than 100 degrees. The subplot involving Ron's birthday had been conceived by the Parks staff early in the development of the show. Series co-creator Michael Schur called a final scene with Leslie and Ron, in which the two voice their mutual admiration for each other, his favorite of the season. "Eagleton" also featured a guest appearance by Eric Pierpoint as the Pawnee police chief Hugh Trumple and a cameo by Mike Scully, a writer and producer with the Fox animated series The Simpsons who has also previously worked on Parks and Recreation.

"Eagleton" received generally positive reviews and, according to Nielsen Media Research, was seen by an estimated 5.06 million household viewers, an increase over the previous original episode, "Jerry's Painting".

Tom informs the department that Eagleton, a more prosperous neighboring town of Pawnee, has erected a tall fence in the shared Lafayette Park to keep Pawnee residents out of their side. Leslie suspects it is the work of Lindsay Carlisle Shay, Eagleton's parks and recreation director, a former Pawnee parks department employee and Leslie's former best friend. Meanwhile, Leslie has discovered Ron's upcoming birthday, a date he has kept secret for years. Leslie promises a horrified and annoyed Ron that she will throw a surprise party for him.

In a typically rowdy and disorderly public meeting, the citizens of Pawnee demand the fence be removed. Leslie meets with Lindsay, who condescendingly refuses to remove the fence and insults Pawnee in the process. Leslie, Tom and Ben attend an Eagleton town meeting to plead their case to its citizens. The Eagleton meeting is much different than those of Pawnee: it is a catered affair at a country club, where the citizens are wealthy and civil, but also snobbish and condescending. Citing the poor maintenance of Pawnee's side of Lafayette Park, the Eagleton citizens prefer the fence stay up. Leslie reveals to Tom and Ben that she was offered the job of Eagleton parks director five years ago but turned it down, as she and Lindsay both made a promise to remain in Pawnee. However, Eagleton then offered Lindsay the job and she accepted, thus turning her back on Pawnee and Leslie. Meanwhile, Ron becomes increasingly paranoid of Leslie's birthday plans, especially after he overhears April and Andy discuss outrageous party plans. When Ron asks Ann about Leslie's last birthday bash for Ann and learns what a huge party she threw, Ron eventually becomes so paranoid that he resorts to sleeping in his office to avoid any potential surprises at home.

Leslie quickly seeks revenge against Lindsay by getting her parks employees to throw garbage over the Eagleton side of the fence. When Lindsay arrives to stop it, the two get into a fight amid the garbage bags. The police arrive and arrest both women: Lindsay is jailed in Pawnee, while Leslie is jailed in Eagleton's pristine and hotel-like holding cell. After Ann bails Leslie out, she tells her that Lindsay built the fence because she is jealous that Leslie was offered the Eagleton job first and wants to get a rise out of her. Ann suggests that Lindsay should be hit with a baseball bat, which gives Leslie the idea to turn Pawnee's side of Lafayette Park into a wiffle ball field, with the fence serving as the outfield wall. Lindsay is impressed by how fast Leslie turned the fence into something positive, and remembers why she and Leslie joined the parks department in the first place. With their relationship on the mend, the two agree to get a drink together. Later, Leslie returns to the office to throw Ron's party: she takes him to an empty room with steak, whiskey and his favorite movies waiting for him, and reveals that April and Andy's duties were false leads to trick him. Leslie explains she made a party that he would want and leaves a content Ron alone to enjoy his birthday.

Parker Posey, who previously worked with Amy Poehler on the 2009 comedy film Spring Breakdown, described herself as a fan of both Poehler and Parks and Recreation, and had wanted to make a guest appearance on the series even before it first aired. Posey discussed it with Poehler at the Spring Breakdown premiere during the 2009 Sundance Film Festival in January 2009, a few months before the first season of Parks debuted. She later met with the staff of the show about one year before "Eagleton" was filmed. After several months without an invitation to appear on the show, Posey said she became frustrated and stopped watching the show, but later changed her mind and started watching it again. Shortly after that, she received an e-mail message from Poehler inviting her to play Lindsay Carlisle Shay: "She said, 'You'll play my nemesis! We get to fight in a garbage dump!'" Posey said. "I remember reading that and thinking, 'Dreams do come true.'"