For her role as Diane Chambers on the sitcom Cheers,[2] Long received five Emmy nominations, winning in 1983 for Outstanding Lead Actress in a Comedy Series.

[4] Long reprised her role as Diane Chambers in three episodes of the spin-off Frasier, for which she received an additional guest star Emmy nomination.

In 2009, she began playing the recurring role of DeDe Pritchett on the ABC comedy series Modern Family.

[5] She is the only child of Ivadine (née Williams), a schoolteacher, and Leland Long who worked in the rubber industry before becoming a teacher as well.

Long's break as an actress occurred when she began performing in local commercials for Homemakers furniture store in the Chicago area.

In 1975, she began writing, producing, and co-hosting the television program Sorting It Out on WMAQ-TV[9] and went on to win three Regional Emmys for her work on the show.

In the same year she guest starred on Family and Trapper John, M.D., and played Nurse Mendenhall in an episode of M*A*S*H.[12] In 1980, she appeared in her first feature film role in A Small Circle of Friends.

Although she had already been in feature films, Long became famous for her role in the long-running television sitcom Cheers as the character Diane Chambers, who has a tempestuous on-and-off relationship with Sam Malone.

"[17][18] Long said in later interviews that it did not occur to her, when deciding to leave, that she was going to "sabotage a show" and she felt confident that the rest of the cast could continue without her.

[19] In a 2003 interview with Graham Norton, Long said she left for a variety of reasons, the most important of which was her desire to spend more time with her daughter.

In a 2007 interview on Australian television, Long said Danson was "a delight to work with" and talked of her love for co-star Nicholas Colasanto ("Coach"), who was "one of my closest friends on set".

[28] She later resurfaced as Diane in several episodes of the Kelsey Grammer spinoff series Frasier, for which she was nominated for another Emmy Award.

[29] Both Outrageous Fortune co-star Bette Midler and Paramount studio executive Richard H. Frank, who helped develop Cheers, described Long as being difficult to work with.

[29] Long guest-starred in several TV shows such as 8 Simple Rules, Yes Dear, Strong Medicine, and Boston Legal.