2006–2011: Acting work and directorial debut
Westfeldt's next feature, Ira & Abby, marked her first solo screenwriting effort. The film debuted at the Los Angeles Film Festival in 2006, where it won the Audience Award for Best Feature. It was acquired by Magnolia Pictures and released in the fall of 2007 to strong reviews. Westfeldt won Best Actress at the HBO U.S. Comedy Arts Festival in Aspen in 2006 for her performance as Abby, where Ira & Abby also took home the Jury Prize for Best Feature. The film won Audience Award for Best Feature at the Boston Jewish Film Festival.
After one season on Two Guys, a Girl and a Pizza Place, 20th Century Fox Studios cast Westfeldt as the lead of another series, the short-lived Holding the Baby on Fox. She went on to star in multiple pilots, including the WB's The Gene Pool opposite Chris Eigeman; The Untitled Paul Reiser Pilot on F/X; and Steve Levitan's Dante on NBC, opposite Morris Chestnut and Kevin Hart. In 2002, Westfeldt, along with her journalist sister Amy, sold a one-hour newsroom drama pitch to Touchstone/ABC; Westfeldt was attached to star. Called The Independent, the series was loosely inspired by her sister's experiences as a career journalist at the Associated Press. In 2006, she was cast as the female lead in ABC's Notes from the Underbelly, which ran for two seasons. Andrew Johnston wrote in TimeOut: "Jennifer Westfeldt is a total babe, with physical-comedy skills that, if properly honed, could approach Lucille Ball territory. In other words, she was basically born for TV. [Westfeldt] gets to show her serious side, too, and if the series gives her enough exposure to start competing with Hope Davis and Laura Linney for blond-WASP roles, Underbelly will have more than justified its existence." In 2010, with Alan Ball attached as executive producer, she sold a TV dramedy to HBO with her attached to star about the bird's nest custody agreement in divorce cases.
In 2011, Westfeldt wrote, produced, starred in, and made her directorial debut in Friends with Kids, which was a breakout hit at the 2011 Toronto International Film Festival. Lionsgate and Roadside Attractions obtained the rights to the film, and it was released in 2012. Westfeldt starred opposite Adam Scott, with a cast including Maya Rudolph, Kristen Wiig, Chris O'Dowd, Ed Burns, Megan Fox and Jon Hamm. Peter Travers of Rolling Stone called Friends with Kids "an indelibly funny and touching comedy with a real sting in its tail," and deemed Westfeldt "an actress of rare wit and grace, and now a filmmaker with a keen eye for nuance. In front of the camera and behind it, she's the live current that pulls us in and makes us care. Westfeldt is the pulse of Friends With Kids, presenting us with life in all of its vibrant, messy sprawl." The film was included on New York Magazine's Top Ten Movies of 2012 list, as well as NPR's Top 12 of 2012.