Barr's other writing credits included episodes of Parker Lewis Can't Lose and Weird Science before his longest stint, as one of the main writers for Will & Grace (on eighteen episodes between 1999 and 2004), usually credited as a producer as well (supervising, co-executive, or co-producer). Because of the latter, he shared in the series Emmy Awards win in 2000 for Outstanding Comedy Series, and he also wrote for the revival series.
Barr also wrote episodes of Desperate Housewives, The New Adventures of Old Christine, and The New Normal.
- Episode 307: Germ Warfare
- Episode 311: Wilderness Weekend
- Episode 320: We Are Not Alone
- Episode 401: Monster Under the Bed
- Episode 403: The Greatest Story Ever Sold
- Episode 404: Driving Miss Ethyl (with Tim Doyle and Jane Espenson)